3/19 I read the link someone posted about Wolfram vs. Kahan. So maybe I'm
ignorant, but it seems to assert that (1/r)^x r^x, for arbitrary r, is
not 1. So, why not? Is it because of r=0?
\_ yes.
\_ KAHAN WINS! GENGHISALITY!
\_ Fractional powers can't be defined in a single continuous way for
the whole complex plane. You can define a principal value, but
it screws up equations like the above. E.G. r=-1, x=.5
(-1)^.5 * (-1)^.5 = i * i = -1 != 1
\_ Partha, would you please write an article describing W-vs-K?
\- "go ask william what the wolfram said" ... talking to kahan
is pretty much a guaranteed interesting experience. --psb
\_ Some of us are do not live in berkeley anymore ....
\_ And that was definitely the most exciting part of the entire 20th
century!! Yes, indeedy!

3/18 I have a question for you theoretical CS types out there. Has Stephen
Wolfram ever actually contributed anything significant to the field
of cellular automata?
\_ Were you listening to Berkeley Groks too? Wasn't he just
describing CS?
\_ I don't think so. It seems like he tried to take the concept and
apply it to life, the universe, and everything, while being pompous.
\_ When Wolfram was a physicist at Caltech, he did a bunch of
pioneering work in CA (early '80s).
\_ you must be talking about his already refuted, self-published
tome
\- stephan wolfram vs. william kahan in 10evans was one of the
high point of the last century. --psb
\_ high points of the 20th century? okey dokey! maybe you
lived in a different 20th century from the rest of us.
\_ were you there at kahan wolfram 1? i can't speak to
the entire 20th century, but it certainly was one
of the high points of my life. was there ever a
kahan wolfram 2?
\_ don't get out much huh?
\_ What happened?
\_ Partha, for the benefit of mankind, would you describe it?
I am very interested, having been a student of Kahn and
a customer of Wolfram.
\_ i assume he is talking about this:
http://tinyurl.com/2vlae
\- this misses the 1+1 = 3 part. --psb
which doesn't really seem like any sort of highlight
except for flamemongers i guess.
\_ wow! that sure is cool. and to think I was all
excited about the fall of the Berlin Wall and
Communism. What a fool I was for missing out on
the really important historical events.
\_ i take it this means you were not physically
present.
\_ unless someone got stabbed while screaming,
"oh contraire, mon frere!" it isn't important.
\_ Are you talking about A_New_Kind_Of_Science? Have you
read it?

3/1 Computer science trivia of the day:
Say you have X memory and have 8X that size to sort on the disk.
Each time you swap from X memory to one of the 8 pages, it will
cost you n time. Using what you know about merge sort, quick sort,
and what not, what is the complexity in terms of n?
\_ Do your own homework.
\_ I used to know that but then I graduated and stopped spending my
time on useless homework problems. It was O of something.

2/15 Ok we disagree on many issues, but can we agree on something? Start
your list here, and delete any entry you don't like (hence an
intersection of issues we agree on):
-bush is stupid
-math is fun
-linux is better than Winblows
-berkeley is better than Cal State
-berkeley women are uglier than Cal State chix
\_ Rather than deleting, wouldn't it be more fun to start flamewars
under each subject? I disagree at least somewhat with all of
those except the ugly one. It probably applies to guys too though.
\_ are you talking shit about math?
\_ I guess some math is fun, sometimes. I'm a math centrist.
\_ Mushy head!

2/3 Happy 02/03/04!
\_ What the fuck is so happy about it?
\_ If you're a numerology idiot it probably means something to
you. I was chillin with the Tooth Fairy last night. She was
bummed that Santa keeps telling her he's going to file soon but
never does, but she met this oddly cool egg laying Bunny and
went home with him so it's all for the best.
\_ are you guys J0X1N?? This day is so cool... personaly, I'm
counting down to 3/4/05... Pythagorean Day! wheee
\_ Damn bitch. Not bj? She must've watched the Vagina Monologues.
\_ 01/04/09 : Alien Monolith Day!
\_ Ah man, I forgot about Fibonacci day: 01/02/03 5:08

1/28 Slashdot has a story about the DeCSS haiku, which reference's the
CSUA's collection of zinc haiku. What is he talking about? Motd
historians, your city needs you.
\_ ~scotsman/pub/humor/zinc_haikus
\_ Some of you people are getting carried away with the apostrophes.
\_ What than would you have us do? It's better then abuse of the
then/than misspellings. And corrected; sorry.
\_ I hope you know you just made a then/than mistake in that post.
\_ http://www.loyalty.org/~schoen/haiku.html -- my article including
influence of CSUA zinc haiku in my poem about DeCSS. -- schoen

1/2 Computer science question for you PHDs out there. What would be
the feasibility of a program that, given a set of images that form
a mosaic, produce the "most correct" composite image, based upon some
definition of correctness that could be supplied in advance (color
compatibility, smoothness of lines, etc)? For instance, such a
mosaic could be a 360 series of photos that form a panoramic
photograph. Such a program wouldn't necessarily need to be perfect,
and any of amount of "hints" could be given to the program as well
as the input images. This might already exist, or it might be solving
the halting problem - I don't know. I'm asking the question for a
materials science post-doc friend of mine that is working with
crystal lattice images. --lye
\_ Does the camera rotate as it takes pictures? Is there overlap
between individual images? At its most general, this problem
involves object recognition and so is vision-hard.
There are some papers on this problem, google for obvious things
to find them.
\_ such programs exist. if the camera undergoes pure rotation
and no translation about the optical center, the problem is
very easy to solve (assuming overlap between the views). other-
wise it's harder and you have to rely on some kind of
approximation because you need to know the 3D geometry of the
scene. other things that help: if you know the exact motion of
the camera, the problem is easy again. -ali
\_ There is a ton of literature on this kind of problem, which is
known as "registration." A standard approach is to define some
kind of error function (distance between edges, or distance
between overlapping pixels in color space, etc) and try to minimize
it over the space of transformations. An algorithm that works well
for a lot of problems of this type in the pairwise case is called
"iterative closest point," due to Besl and McKay. If you don't
know an approximate solution to start with, it is a lot
more difficult. -lewis
\_ homeslide, iterative closest point requires you to know
the 3D geometry of the scene to perform registration.
altneratively, you need some kind of parametric transformation
model for your images.

12/3 Did anybody catch the Nova series on PBS a month or so ago on
String Theory? What do you think of it? Is this Witten guy really
that smart? He looks a bit phony.
\_ Dunno about string theory, but string practice: ~john/ringback.jpg
\_ Hot. Who's she?
\_ why the fuck do people keep talking about this goddamn show?
If you want to know about string theory, for some godforsaken
reason, read a fucking book.
\_ somepeople want a lay person's explanation to be done in
an hour. Books take much longer than that.
\_ How about http://staff.science.uva.nl/~rhd/string_theory.html
\_ I'll sum it up in two lines on the motd:
If a theory is unrelated to experiment, it's not
physics, it's philosophy.
for more information type "dict wank."
\_ Apparently you're a wank wannabe scientist who's never
read Kuhn. --williamc
\_ I heard there may be experiments with the potential
to falsify string theory coming after the CERN accelerator
comes online in 2006. -- ilyas
\_ right, and when they do, the theory will either
be falsified or just unverified. wake me when
they can calculate the mass on the electron from
frist principles or predict a new particle
acurately, or do *anything* predictive. <snore>
\_ We will eventually run out of things to predict.
A theory isn't good only if it predicts something new
(although that's really nice). A theory is good
if it doesn't contradict any data and is as small
as possible. Personally I know next to nothing
about string theory, and lack the background to
learn more. I don't know how well it fits, and
I don't know how small it is (or why there's so
\_ How about http://staff.science.uva.nl/~rhd/string_theory.html
much hype). -- ilyas
\_ wow, this is the first time i heard this show mentioned. i must
be out of it. anyway, go read Brian Greene's "The Elegant
Universe." it gets pretty dense as you get into it, but given
enough dedication, you can follow what he's writing.
\- the Witten/Schwartz/MGreen(not BGreene) is a pretty standard
serious work on string theory: http://csua.org/u/557
witten solved a problem a bunch of other people were
stuck on [i think this is descrived in vague terms in
the show, but i saw it a only in part and a while ago]
annd he's not doubt a bright guy ... but personally i
find s. weinberg more impressive and certainly more
articulate. "dreams of a final theory" is a more accessible
but still interesting book. it's also cheeper than the
GSW book ... which is a $50 "paperback" and fairly tough
going if you dont have say 2yrs of grad math. --psb
\_ did anyone in this thread express interest in
a "standard serious work?"
\- dear mr. too short: "phony physicists rarely write
standard serious works". --psb
\_ fuck off. -real physicist
\_ you lie. a real physicist wouldn't call herself
such (maybe "physics grad student" or "physics
prof"). i wont make judgments on whether she'd
be posting to the motd.
\_ doh! you got me! it turns out that i'm the
pompus ass sysadmin knowitall who learns
about the most useless theory in physics
to impress girls at parties, and you're actually
the physicist! my bad!

10/30 Yahoo! News - Robots to Gain Eyes in the Back of Their Heads
htt://csua.org/u/4um
It reads " But as computer scientists at the University of Maryland
proved mathematically in 1998, if robots could see in all directions
they would not need any other sensors." What kind of mathematical
proof would that be? How do you go about proving something like this
mathematically?
\_ why doesn't evolution favor eyes at the back of animals heads?
\_ Prey animals usually have very widely-spaced eyes and can see
in almost 360-degrees. Predators (and humans) have forward
facing eyes which give good depth perception. Why do no
vertebrates have more than 2 eyes?
\_ The fundamental answer guiding all evolutionary processes:
efficiency.
\_ only able to last 15 seconds in the sack, eh?
\_ How is turning the head to look behind more efficient than
procesing more signals from more eyes in the brain?
\_ You save the energy needed to grow more eyes and the
brain structures needed to process the extra input.
\_ But you need to grow the muscles to turn the head,
and for some mammals, even part of the body.
\_ good point.
\_ Eyes have a lot of muscles and things, at least our full
functioned ones do. Also, head movement is needed anyway
for eating (maybe not for humans, but for prey animals).
Since prey animal eyes and hearing suffices, more eyes
probably cause more problems than they help. They might
also be vulnerable to injuries. Head movement is also used
for smelling.
\_ You might also want to take into account that more
eyes also translates to more brain mass/complexity
to process the information.
\_ Flies have many eyes in two groups.
\_ I said VERTEBRATES.
\_ and mammals (and many verterbrates) have many rods/cones
in two groups.
\_ But flies have many separate lenses whereas mammals have
only two.
\_ The article explains it pretty well:
"The ability to navigate was the lowest level of capability
needed by a robot to work in an unknown environment, she said."
"Providing a robot with "omni-directional" vision could vastly
improve its navigational skills, ..."
Thus, you make the assumption that navigation is needed, then
you prove that 360-degree eyes are sufficient for navigation,
thus it doesn't "need any other sensors."

10/13 Second WALKING robot out of Japan. First one was Honda's ASIMO.
http://www.sony.net/SonyInfo/QRIO
Is anybody else even in this field?
\_ learn to scroll. Specifically, downwards.
\_ More importantly, why bother being in this field? Is building a
robotic version of a human really all that useful? I'd rather
have numerous cheaper specialized robots than 1 general purpose
one that can sort of do a number of things ok. Like it would be
nice if my vacuum cleaner would just turn on and clean up when
I'm not around and then go back to it's closet.
\_ Or a robot grammarian. \_ its god damn it. it's not hard
\_ I think such vacuum cleaner aleardy exists.
\_ Or a robot grammarian.
\_ Wait until they have sex slave robots made in the image of
your choosing. Then you'd have something.
\_ Wasn't the first one a Honda/Sony joint venture?

9/5 I have a relatively large mailing list archive in a
typical unix's mbox format. Is there any tools that
allow me to view it easily, i.e. reconstruct threads, etc?
\_ mutt -f file (then hit "ot" to sort by threads)
\_ From a mh perspective, you can incorporate it into your mail box
with inc, and then do a subject field sort with
'sortm -textfield subject'. -ERic

2/13 How about a little academic anti-bragging? Let's poll how low your
SAT/GRE score was and how well you did in school. Do not reply if you
had a high score. For me, I was an EECS major and I had a SAT of
1300. My math was an abysmal 680. I think I was the only EECS guy
with such a low math score. I did ok in school (some As, mostly Bs).
\_ In high school, 670 Verbal, 720 Math, 3.98 GPA.
Graduated Cal with a 2.74. Fucking ouch.
\_ I think he wanted the other way around. I know a lot of people
including myself who were good in HS but fucked up at Cal. I
think it had more to do with peripheral issues than actual
academics. I did well when I tried, but I had a hard time
enjoying and motivating myself there. Although having Cal on my
resume helped with job interviews, what with my shitty experience
and having to explain shitty grades I should have gone elsewhere.
\_ I failed every single math class after junior year in high school.
\_ I graduated with a 2.3 GPA.
\_ got in with 1200 SAT, English major, graduated with a 2.8. I'm
making 6 digits as a sys adm.
\_ 370 Verbal, 780 Math. Graduated with honor in L&S CS with 3.65.
(Now guess my ethnicity.)
\_ Asian, Eastern European, or white nerdling who lived in a cave.
\_ 540 Verbal, 670 Math, and got into EECS. I thought hell would
freeze over before I got into EECS with that score, but it happened.
My guess is that I got in for geographic reasons. I came from
Modesto, and in general the Central Valley is under-represented in
terms of % of people in California. -phale
\_ I scored a lot higher and didn't get in. --white boy
\_ Well, my SAT was okay, but my GPA wasn't so hot. I wasn't even
within the top 40-percentile of my class, yet I still got in.
\_ are you a protected minority?
\_ no. i think i simply got lucky.
\_ there's a small quota for "low end white people" too
\_ 640 verbal, 730 math, Entered Fall '85 EECS
\_ Oh, 1370! How shameful! This is supposed to be anti-bragging.
\_ yer supposed to say "apparently your verbal score is
overinflated, because ...", or "yermom accepts all
applicants regarless of SAT score"
\_ 1410, l&s, non-cs, below 2.7 gpa, making well into 6 figs
\_ 1320, foreign student, didn't finish high school because we end
in december, used 10th grade exam results to apply, our
grades are like a1, a2, b1, b2, didn't know how to translate
to gpa, so I just considered both a1 and a2 as 4.0, which
made my gpa 4.0. they did get my transcript though so they
can see everything. had one semester of 9th grade in the
US and got a 4.0, so that might have helped. Cal at first
wanted my 12th grade exam results, but I ask them not to be
so picky, so I got in, but UCSD rejected me for unknown
reasons. Cal was pretty tough for me (B), but many of my
fellow countrymen did really well at Cal, most with > 3.5 gpa,
one with 17 A+'s in EECS.

8/19 Machine learning people: what would you recommend for a reference
on pattern classification? It seems Duda & Hart is the classic,
but it's 30 years old -- is it still relevant? Any other
exceptional texts? Thanks.
\_ Tom Mitchell's book Machine Learning?
\_ I am told there aren't exceptional ML books. Stuart used
Mitchell's book, and Bishop's neural network book.
\_ if you want something not very mathematical, there are plenty of
books out there that will teach you how to use a given
software package to do what you want.
if you want to understand what's happenning, i really like
Hastie, Tibshirani and Friedman's book, the Elements of
Statistical Learning. Duda&Hart is outdated and is pretty naive:
there are lots of interesting links in ML, and D&H does not
notice them (even the second edition, which is significantly
revamped). Bishop's is very nice, but it doesn't cover a lot
of topics. i haven't taken a good look at Mitchell's book, but
i would pick hastie/tibsh/fried if i had to teach a class.

7/30 Any math major here? There was a claim that "a^n + b^n = c^n has no
positive integer solutions a,b,c,n for n > 2." Ten years or so ago I
heard that nobody has found yet either a proof or a counter-proof for
this statement. Is it still the case today? Thx.
\_ Is this the theorem that some enlightenment-era math
type (Fermat? Euler?) claimed to have proven in the margin of
one of his journals? If so, I believe it was solved recently
by a British guy using some rather advanced number theory.
I'm not at all a math major, but I remember the story--
supposedly Fermat/Euler/Whoever couldn't have proven it because
the background theory or methodology didn't exist back then,
and people seemed to believe that F/E/W knew he hadn't proven
it, but claimed to have done so because he thought it was
provable and wanted someone else to do it. Apologies if I'm
way off.
\_ It was Fermat's Last Theorem, and he claimed to have a "truly
remarkable proof" that would not fit within the constraints
of the margin. Euler tried and failed. The British
mathematician actually failed his first time, but then came
back with a proof a year later that has since been accepted.
It wasn't that it was impossible that Fermat had the proof,
only that the British guy used something entirely different
from what everybody else was trying to use, he did not use
number theory.
\_ It's not really accurate to say that Wiles ("the British
mathematician") "failed his first time." Even in between
the time a gap was found in his proof, and when he was
able to fix it, most experts thought the proof was
essentially correct. It would have been truly astounding
if a manuscript that large and that original had been
perfect the first time around. Also, I'm not sure what
you mean by "he did not use number theory," since the
whole paper is number theory. It is true that he used
lots of concepts that were not known in Fermat's time.
\_ it still cannot be proven in Star Trek TNG, so it's hopeless
now. ;)
\_ "I love you, but I do not love you!"
\_ "This statement cannot be proven."
\_ It has been proven recently, after 300 years or so of failed
attempts and false proofs. Search google for "fermat's last
theorem" for details.
\- this was a troll, right? anyway, the people working on
the FLT were really working on deeper conjectures like
the ABC conjecture ... the FLT would have been a small
byproduct. the people who claimed to be working on the
FLT itself were probably cranks. berkeley's K. Ribet
was a big player in this story. --psb
\_ There's an episode of Nova where he is talking about
FLT at Caffe Strada.

7/19 http://www.discover.com/aug_03/gthere.html?article=feattech.html
Maybe in another 10 years this sort of thing plus the advancement of
computer graphics in general will lead to all hollywood movies being
done on computer and the end of the super rich empty headed hollywood
actors running around mouthing off on late night talk shows.
\_ You forget that all the animated features use big celebrities
for voices. Computer-generated speech will suck for a long time
to come. -tom
\_ I'm not going to recomend it as a *good* movie exactly, but
the movie "simone," with Al Paccino explores this idea.
\_ Oooh! Genetic algorithms! Must ... put .. on cover ... of wired..
\_ Here Here to that. I was hoping to give them all a 9mm hemmorage 1st
\_ First of all it is hear hear. Second of all wow aren't you a
big man. I bet all the chicks flock to your manlyness
\_ But then whose lives will we vicariously live?
\_ yes we need good down to the earth "real" looking
guys like Eric Raymond on the tonight show
\_ WTF would anyone put a geek on a talk show? Maybe they'd start
putting interesting people on them instead of entertainment
figures or better yet just cancel the entire late night genre.

6/5 Someone explain the big-O notation again. Basically O(X) means
a computation cannot be worse than constant*X, where X could be
log, exponential, or what not. So isn't it correct to say that
the big-O for quick sort could be any of the following: O(nlog n),
O(n^2), O(n^n), O(n!), since quick sort will never be worse than
these?
\_ all of those are technically correct (except for O(n log n),
quicksort is O(n^2) in the worse case). however, when your
characterization of the running time is that far
off from the true upper bound, that's not very useful.
\_ you should look into the difference between big-O, big-theta
and big-omega notation. I believe SICP and CLR(S) both have
decent introductions. --twohey
\_ http://www.cs.mcgill.ca/~cs251/OldCourses/1997/topic3
\_ no because that suggests it could actually be of n! time
which it can never be. (unless u implement it wrong)
\_ if you implement it wrong, it shouldnt be called quiksort, it
shoudl be called slosort or something like that.
\_ how about "spellsort" or "sloppy, lazy typo sort"?
\_ If you can give a girl the big-O - youre set.
\_ But only if you can do it in 0(n) time.

5/25 Dear nice math helper person, I found this from my old CLR book:
Sigma k=0 to n of x^k = (k^(n+1)-1) / (x-1).
Can someone please repost the question I posted yesterday? Thanks...
\_ Almost --- the "k" on the RHS should be an "x".
Hint 3. Figure out how to use this to get a closed
formula for 0*1 + 1*x + 2*x^2 + ... + n*x^n

5/24 How would one solve the following equation?
Sigma i=1 to log n of (2^i * log 2^i)?
I just need hints to get started. I'm not sure if I can actually
use the formula n*(n+1)/2. Please help me get started. I'm not
looking for an answer, just hints, THANKS!
\_ Hint 1. Rewrite log 2^i as i*(log 2)
Hint 2. Find a closed formula for
1 + x + x^2 + ... +x^k
Hint 3. On request.
\_ Ok so I tried hint 2, (2*1)+(4*2)+(8*3)+...+nlog n.
Now what?
\_ Try again; we want a closed formula for
1 + x + x^2 + ... + x^k, i.e, a formula
without the "..."
\_ uh, (x^(i+1)+1)/2?
\_ Nope.
\_ isn't this in first year calculus/math1a?

5/20 How important are course evaluations, and specifically
the evaluations of the professors, for faculty promotions
at Cal?
\_ depends on the dept. all depts read them, regardless of
whether the prof does. be fair and don't froth at the mouth;
instructors (and depts) can ID and tend to discount wildly
angry evals unless it's clear that those evals can support
their claims. wildly positive evals tend to be discounted
too. :) --humanities gsi
\_ Yes, it depends *alot* on the department. I think the
Berkeley math department really doesn't give a shit about
teaching. I majored in math, and got to see a bit about how
that department works and how they do their hiring. When
you apply for a faculty position there, they don't even ask about
teaching experience. Of course there are some great teachers,
like John Neu, but they decided to be great teachers on their
own, with no motivation from the department.
\_ And now the truth: you're an undergrad at a research university.
Unless you have film of the prof molesting 6 year olds just before
killing them in a satanic ritual (and his face better show) your
eval won't mean anything to anyone. The translation of the above
about ignoring the angry and the happy people is that the only evals
remaining are the vast bulk that say very little. Think about it.
\_ not ignoring all the non-bland ones, just discounting those
which sound stalker-like (at either end). there's a
difference. the research univ. emphasis is correct
otherwise; ucb does care more about teaching across
the board than many comparable research schools, both for
hiring and internally, but that's nothing to the fuzzy
warmth of small colleges. one's teaching record can help
for advancement but it rarely hurts enough to prevent
advancement. if you've a serious contention re: someone's
teaching, take it to the dept chair--they hold office
hours like anyone else.
\_ holy shit, no! do not go to the department chair! not if
you ever plan to take a class with that department ever again.
\_ If the professor is good or has tenure your evaluation forms
probably aren't going to negatively affect his career much.
Do you really expect one grumpy undergrad to matter that much?
However a lot of professors actually DO care about teaching well
and evalution forms do help them with that. Also departments who
have profs that have a history of getting really bad evals tend to
work with that in mind. For instance I think the famous Hurricane
Wu no longer teaches undergrad classes. And that is the math
getting much funcding yet expected to give almost every undergrad
department which is famous at cal for not giving a damn about
the undergrads. (Probably something to do with that whole not
getting much funding yet expected to give almost every undergrad
here a year or more of math.) Also as has been said, good
evaluations help more than bad ones hurt. So give good evalutions
to the profs you like, give constructive critisism to the ones
you think will actually listen, and don't stress too much.
\_ Mostly agreed. Bottom line, be honest, but be mature.
\_ I was in Wu's Math 1B class for about 3 minutes. That's how long
it took to realise the guy was a total psycho and walk out even
though I needed 1B that semester. I couldn't believe no one else
left. Did anyone else here actually take Wu for longer than a
week?
\_ Actually, a friend of mine took his upper division
differential geometry course and loved it. of course he
is also insane, and is now getting a phd in differential
geometry. For some people, Wu is actually a very good
teacher.
\_ Pulled a B. Worst semester ever. --scotsman
\- The time has come for:
http://www.jiggscasey.com/slappy/book_of_wu.html
--psb
\_ NOW THAT IS HILARIOUS. Is Wu REALLY like that
in person? All that cryptic Chinese proverb shit?
\- everyone i have pointed to that page
thought it was funny. everyone who had
wu for a class also added "it was really
like that!" The other funny thing is Wu
rally cares about teaching. If you go to
his WEEB site, he's written papers on
*teaching* math. ok tnx. --psb
\_ Now you know why you have fans.
\- PSB's Corollary to Godwin's Law: All conversations
about teaching at Berkeley eventually end up at
Hurricane Wu. --psb
\_ Wu, Math 113... Hard as all hell.

4/22 Data Structure: X,Y,Z coordinates repeated. Same X,Y - different Z
Ie, multiple surfaces over the same grid. Problem: Want a polynomial
fit f(X,Y)=Z; save the equation in matrix/vector; then the dump into
MATLAB. Question: a lot of programs do polynomial fits, but it
seems to be a pain to save the equation describing f(X,Y). What can
I use to do a large number of curve fittings and then save the
polynomical eqn? fab@csua
\_ If you took CS170 you should know the answer to your own question.
Hint: it starts with an F, and runs in O(n log n) time.
\_ Didn't take CS170. Care to provide an answer? The question
isn't about curve fitting, it's merely about making
your favorite software (Stata, SPSS, MATLAB, etc)
produce a friggin' macro/list/whatever. fab
\_ The data structure itself can be used to represent the
fitted polynomials. You can transform between a 'set of
points' representation and 'set of polynomial coefficients'
representation using something called Fast Fourier
Transform. I highly suggest you read up on it, any
engineer should know what it is.
\_ I'm not an engineer. Sorry to disappoint, but if
this is routine, I wouldn't mind paying some undergrad
a very modest sum to do this for me. fab@csua
\_ Dear fab@csua. Are you really stupid enough to
not realize you just offered someone a very modest
sum to do nothing at all? The whole point of FFT is
that your original matrix is a perfectly valid
representation of the fitted polynomials.
\_ I think it's a reasonable guess that anyone
not clever enough to indent motd correctly
may not be clever enough to do FFT's.
\_ I took 170. We didn't cover that. Must be new math.
\_ Boy, there are a lot of wrong answers here. FFT does
NOT fit polinomials to data. It fits discrete complex
sinusoids to it. This almost certainly isn't what the
person wants. Your belligerence is unwarranted, and
surpassed by your ineptitude, mr. fft guy.
The op should consider performing the polyfit in MATLAB,
instead of worrying about how to dump the result to
MATLAB. the polyfit function in matlab does this. Also,
I don't understand your question, so what nivra said -ali.
\_ http://www.mapleapps.com/categories/mathematics/algebra/html/FFT-Polynomial.html
\_ this teaches you how to use the FFT to multiply two
polynomials. the trick is based on the fact that
convolution of the poly coeffs is the same as
multiplication of the DFT coeffs. it has nothing
to do with polynomial fitting. did you just google
for "fft and polynomial" and post the result on
the motd? -ali
\_ I don't get your question. It seems you're asking for the
following: You have n-mesh like 2-D surfaces, you'd like a
polynomial fit for each surface, resulting in n-sets of polynomial
equations Z = f(X,Y), You'd like to save all n equations easily.
Most polynomial fits should give output in terms of coefficients.
These coefficients form a vector: eg. Ax^2+Bx+Cy^2+Dy+Exy+F.
You will end up with n sets of coefficeints. You can save this
as a big matrix in Matlab. What's so difficult about this? If
you want to do multiple polynomial(2nd order - 10th order) for
each mesh surface, you run this whole thing 9 times, and get
1 matrix for each order, with higher order polynomial fits having
many more vector elements. -nivra

3/19 Just in case some of you haven't seen this yet, there are two
new attacks on RSA in OpenSSL
1. Timing attack on RSA keys:
http://crypto.stanford.edu/~dabo/papers/ssl-timing.pdf
OpenSSL advisory is here:
http://www.openssl.org/news/secadv_20030317.txt
2. Extened Bleichenbacher attack on RSA with PKCS #1 v1.5
padding:
http://eprint.iacr.org/2003/052
The OpenSSL advisory will be here:
http://www.openssl.org/news/secadv_20030319.txt
\_ In English, if I'm a low value target do I have to worry about
anything? Is this stuff theoretical or script kiddy quality?
\_ the dropouts speak!
\_ Read the Stanford paper. They have an exploit. They also say
which configurations are vulnerable. Now set up a traffic
monitor/packet sniffer on your "low value target" home DSL or
cable box and fire up IRC or something. Enjoy. -John
\_ If you are running HTTPS on your "low value target" I would
recommend applying the OpenSSL patch that fixes the first
attack. I wouldn't be as concerned about the second one.
In any case, if you are running OpenBSD 3.1 or 3.2 there
are patches available from the usual place.

12/18 Math help! I'm a software engineer who forgot how to do problems
like this: I have a bag with 60% black marbles and 40% white.
Drawing with replacement, how many marbles do I have to draw to
have a 90% chance of drawing 5 black marbles (among any number
of white)? I'd appreciate a formula or explanation because I might
need to change those numbers. THANKS!
\_ Stat 2, kids.
\_ Couldn't you figure this out using your own logical reasoning?
\_ No, that is why I am asking.
\_ Likely wrong:
* Drawing 5 black marbles on the first try is .6**5 = .07776
You want to make the chances of 5 black marbles .9, ie,
* .007776 * numDraws = .9
==> numDraws = .9 / .07776 = 11.57
==> rounding up, you need 12 draws.
\_ When you can't find the right forumale, the easy backup plan
is to write a program that will do X trials for you and find it
empiracally.
\_ Real answer:
The answer is the smallest N, such that the definite integral
of the binomial distrubution function with parameters n = N,
\_ too bad you can't take a definite integral
of a binomial distribution -- it's discrete.
\_ What the hell are you talking about? Of course you can.
Just take the sum. You are an idiot. Go away and kill
yourself now.
\_ So do a discrete summation instead
\_ Too bad there are only five marbles in the bag (3 black and 2
white) making a solution impossible. Unless you know the number
of marbles in the bag, you can't give a reasonable answer. As it
approaches a very high number (not infinity per se), the above
solution becomes more valid.
p = 0.6, taken from 5 to N >= .9. Feel free to play around with
many java applets of the binomial distribution to find out what
N is.
\_ you can also use the chernov bound to bound this integral from
above. if you're interested in these specfific parameters,
you should implement what the above says.
\_ It's a poly time algorithm to find N, no need to bound.
\_ The question is asking drawing exactly 5 out of N, so should the
answer be just: 90% = C(N,5)*0.6^5*0.4^(N-5)?

12/9 Story on Blum at
http://www.nytimes.com/2002/12/10/science/physical/10COMP.html
Question - why is Blum "Professor Emeritus" of the CS dept when in
fact he was happy enticed from Berkeley and is now ensconced at CMU
with a full and productive lab?
\_ Hey man, like what a traitor! I can't believe that! I'm just like
ya know totally stunned and completely bummed! And like he ya know
stole an emerity thingy from us! Man!
\_Who said anything about him being a traitor? Just wondering
why he has this title, which means "Retired but retaining an
honorary title corresponding to that held immediately before
retirement" when he's anything but retired.
\_ From Webster's Revised Unabridged Dictionary (1913) [web1913]:
Emeritus \E*mer"i*tus\, a. [L., having served out his time, p.
p. of emerere, emereri, to obtain by service, serve out one's
term; e out + merere, mereri, to merit, earn, serve.]
Honorably discharged from the performance of public duty on
account of age, infirmity, or __long and faithful services__; --
said of an officer of a college or pastor of a church.
\_ enticed by his wife, no less.
\_ yet another reason why marriage is evil. - bdg fan #3

11/15 New developments in quantum crypto:
http://news.com.com/2102-1001-965957.html
\_ new? hardly. would you like a list of references from the
last several years of experimental advances in quantum crypto?
moron reporters report all science as a "breakthrough" to
get the attention of their moron editors.
\_ Even if it was new New NEW! it wouldn't matter one whit to you as
the man on the street. This is only good for big governments and
corps with *lots* of money. It does not work over the public net.
\_ ah. but i am not the man on the street, and it does matter
to me. I work in this field, which is why i get annoyed by
shitty journalism. if you want to follow what's happening
in the field in real time, see the links from the quantum
coherence section of http://www.vjnano.org or just check
Science and Nature regularly.
\_ The rest of us are unlikely to ever see this in real life.

11/7 Anyone have a good intro (i'm in math54 atm) to bayesian analysis
that a college sophomore could understand? i read that the new
spamassassin uses it (like ifile) but cant find a good intro text on
it other than:
http://www.paulgraham.com/spam.html
(which was actually pretty good)
\_ If you are talking about that stupid /. thing, it's really simple.
It's just counting words. If a document has lots of words deemed
'spammy', it does not get through. This is literally all there is
to this 'bayesian' approach. AI people call this the 'naive bayes'
algorithm.
\_ i dont read /. -op
\_ does spamassassin actually use this already? If so, how do I slap
it around and tell it which is spam and which isn't?
\_ the beta/experimental release (2.5) does.
\_ Bayesian analysis fundamentals are simple. It all drives off of
Bayes Theorem (mathworld has one, but there are plenty of better
ones, if you google for it: http://mathworld.wolfram.com In a
nutshell, given the observation of data D, the probability that a
hypothesis is true is equal to the conditional probability that the
data is true given the hypothesis * the PRIOR probability of the
hypothesis being true. In essence, it ideally redistributes your
prior probability distribution based on the data observed. Bayes
Theorem: P(H(i)|D) = [P(D|H(i))*P(H(i))] (formatd was here)
where ---------------------------
D = observ. data Sum(j=1->n,P(D|H(j))*P(Hj))
H(i) = hypothesis i
1<=i<=n -nivra
\_ What's the relation between Bayes Theorem and Neural Networks?
\_ No relationship at all. Neural networks are function approximators
that work using hillclimbing. Bayes theorem is a relationship
between conditional probabilities of two events (it's not actually
a theorem, it just follows straight from the definitions).
-- card-carrying bayesian
\_ Bayes Theorem: Conditional probability. I don't remember Neural
Networks using Bayes Theorem. However, Bayesian networks use
Bayes theory.
\_ I don't know much about Neural Networks. Presumably, they use
different learning algorithms for deciding what information to
weight, and how to weight its nodes/connections. Thus,
presumably, you could have a Bayesian learning algorithm that
decides how to re-weight its connections based on observed
data. -nivra
\_ google for bayesian networks or bayesian belief networks.
Neural Networks typically have an activation function
at the nodes to weight things. The Backpropagation
Algorithm is typically run. I don't think I've heard
of a variation of Neural Networks algorithm which uses
Bayes.

11/7 So, when and where is this LP breakthrough coming out?
\_ The paper was submitted for publication this year. I went to a
talk today given by the guy who came up with it -- the algorithm
is beautifully simple. Unfortunately, I think he is trying to
patent it.
\_ Where was the talk? Where is it being submitted for publication?
Who is the author (or at least institutional affiliation)?
\_ At my school. The author is Andy Mirzaian, from York
University in Canada (received his PhD from Princeton a while
ago).
\_ Did he give details about this algorithm at the talk?
All the details? Were people convinced? Has this work
been subjected to formal peer review?
\_ He described the algorithm, but not the proof that it
runs in poly time. It has not been peer reviewed yet
(since it has only been submitted, not published).
\_ Ah. May I ask which school you are at?
\_ You may.
\_ Which school are you at?
\_ http://www.cs.yorku.ca/~andy/pubs/index.html --google
\_ Yea, got that.

11/6 Strongly polynomial time algorithm found for linear programming.
News at 11.
\_ Uhm, that was 1979. Or are you using some non-standard definition
of "strongly"?
\_ 1979 ellipsoid algorithm was weak polynomial time, i.e. it was
polynomial in the size of the constraint matrix, not polynomial
in the size of largest number in the matrix. The current
algorithm is polynomial in both, which is the standard definition.
What definition are you using?
algorithm is polynomial in both, which is the standard
definition. What definition are you using?
\_ The same one; I hadn't considered the numerical behavior
of the data. So, enlighten me, are you saying the ellipsoid
algorithm can't handle in polytime, say, a matrix with
floats in [0,1]?
\_ No, the ellipsoid algorithm can't handle in
polytime a matrix with really really large
numbers. An easy example of weakly polytime
problem is factoring a dot product vector of
integers. If the integers are small, this problem
is clearly solvable in time linear in the length
of the vector. The problem is that factoring
integers is hard, so there are no (known)
solutions which have polynomial runtime in the
size of the largest integer in the vector. The
ellipsoid algorithm has a similar problem with
numbers in the constraint matrix.
\_ You misunderstood my question. Yes, I know what you
mean by "strongly polytime." What about LP over data
in a fixed range of reals?
mean by "strongly polytime." What about LP when all
parameters are in a fixed range of reals?
\_ I am not sure. If the float is very small, or has
high precision, it will take a lot of bits to
represent it. It may be that in fact the ellipsoid
algorithm has exponential behavior for any number
that needs a lot of bits, large or small. (Note
that this clearly isn't true for factoring).
\- is this one of stephen smale's problems for the next
century? --psb

10/22 http://www.csua.berkeley.edu/~ilyas/problems/coloring
If you know the answer, please e-mail me, but don't give it
away here. -- ilyas
\_ Don't ask us to do your homework for you, mr. cheaty-pants!
\_ I solved this already. I also received one solution from
someone on soda. -- ilyas
\_ "Small" as in fewest vertices or "small" as in some notion
the graph even need to be planar?
sufficient for planar graphs. -- ilyas
of Euclidean diameter or something like that? Also, an edge
can exist if and only if the distance is exactly 1? And can
edges intersect (provided the graph is still planar)? Hell, does
the graph even need to be planar? Can 2 vertices be assigned
to the same position in the plane?
\_ Small in a sense of fewest vertices. An edge can exist
if and only if the distance is exactly 1. Edges can intersect,
the graph does not need to be planar. Two distinct vertices
cannot occupy the same position on the plane. -- ilyas
\_ what's a 4-coloring? Does this question need more explaination?
\_ A 4-coloring is an assignment of colors to vertices, such
that no more than 4 colors are used, and no two adjacent
vertices share a color. The terminology I am using comes
from a related problem asking whether 4 colors are always
sufficient for planar graphs (which was solved by Appel
and Haken with the aid of a computer in 1976). -- ilyas

10/21 By transferring 3.47 gigabytes over 3000 miles (4810 km) of network
from Eugene, Oregon to Syracuse, New York in one hour, the team set
an I2-LSR IPv6 category record of 39.81 terabit meters per second.
is their math wrong or am I dumb? from http://csua.org/u/43a
\_ Their math is fine, assuming they meant, to use the ISO terms,
3.47 gibibytes and 39.81 terabits. note that the former is in
units of 2^30 bytes while the latter is in units of 10^12 BITS.
\- do you know what their %age of re-xmits was and checksum
failures? --psb
\_ Damn. I could stomp this record with a truck full of hard disks.
\_ Never underestimate the bandwidth...
\_ Netflix transfers way more data. Except they use DVD's instead
of HD's and postal carriers instead of a station wagon.
\_ Not in 1 hour coast to coast.

9/17 I have problems with graph theory & combinatorics cuz I didn't pay
attention when I was in school. What's a good book to re-learn these
things (and not to get confused when looking at http://mathworld.wolfram.com)
? Mainly I just wanna understand the Ramsey Number (NP problem) -alum
\_ Take a look at Modern Graph Theory by Bela Bollobas, and
\- hello, there is [was?] a copy of Bela Bollobas:
Graph Theory: An Introductory Course [n.b. this
"introduction" is a Springer GTM] at the 9th ave
Green Apple Book Facility for <$10 ... It's
probably worth a trip to save $30 ... I own one
but probably should have bought it to "arbitrage";
If the book is not useful to you, you can almost
certainly make money on it.
Is that the book you mean above? This is a useful
reference for some of my work but I dont think it
is really a "guide for the perplexed". --psb
\_ Modern Graph Theory is a revised version
of this, with more than twice as many pages.
\_ that's twice as much learnin'!!
A Course in Combinatorics by Van Lint and Wilson. (The
latter doesn't have much on Ramsey numbers though.) -ok
\_ CLR?
\_ I've seen some copies of this pretty cheap on http://half.com.

9/9 Let's say I am writing a multi-threaded email client and I want to
allow for messages to be sorted. Problem: to sort elements I need
all elements and if this thing is supposed to scale retrieving all
messages when changing a sort order will not work. How do real world
mail clients or applications in general deal with this?
\_ you only fetch the headers and sort based on that info...
thats how current clients do it.. you fetch the body when
you actually want to read the message. -shac
\_ I think he was asking "how do i sort this if I've got incoming
email at the same time I'm sorting?".
\_ i actually read that as "retrieving all messages every time
i change a sort order..." which makes more sense... all you
need to do is before you resort check if there are new
message headers, if so then add them, THEN resort. some
mail clients dont even do that.. you hafta tell it to check
for new messages, then resort by date or subject. -shac
\_ yup, that's it. The problem is not re-sorting but
(avoiding) retrieving all messages because there
can be a lot of them and if there are many
users there goes the neighborhood. I can't
retrieve all messages because it's a
web-based client with pagination (think OWA)
so there's a space vs time trade-off and I
am always fetching headers a page at a time.
IMAP server-side sort should solve
this but apparently it's still in experimental
stages... --OP
can be a lot of them and if there are many users
there goes the neighborhood. I can't retrieve all
messages because it's a web-based client with
pagination (think OWA) so there's a space vs time
trade-off and I am always fetching headers a page
at a time. IMAP server-side sort should solve this
but apparently it's still in experimental stages...
--OP [ reformatted - motdformatd ]
\_ Your bad English grammar fu is superior to mine. I bow to
your superior ability to decipher non-English texts and
extract meaning.
\_ no idea how commercial apps do it but as a first cut how about you
sort what you've got and then do an insertion sort on any new mail?
Most folks are mostly sorting on date received so you'll just end
up sticking new mail at the front or back. If you know what you're
sorting on such as date you can take advantage of that fact to speed
things up and "cheat".

7/26 My computer monitor stopped working recently (screen is
completely snowy white). I want to get rid of it, but I'm
not sure if throwing it in the garbage is the best thing to do.
Is there any sort of place that takes in non-working computer
equipment like this? I'm not in the Bay Area.
\_ try throwing it off the top of a parking garage. make sure
you have two escape routes or more.
\_ eBay?
\_ Depends on your community. Your dead monitor has lots of
lead in it. See if your local garbage collector has a program
that deals with dead TVs and monitors.
\_ your monitor is officially hazardous waste, to just toss it in
the trash would be breaking the (poorly enforced) law.
\_ Look around. There are dead computer collection events every
2 or 3 months in my community. I heard some of these get
shippied to China and dumped in inappropriate places, but hey,
that's not our problem right?
\_ computer recycling center: http://www.crc.org
\_ I wish I knew this before I threw away my 386 several years ago.
\_ I also have a broken monitor...it's missing the color blue...
does anyone know the best way to fix this? Thanks.
\_ Did you accidentally mess up the color balance setting on the
monitor? It happened to my cousin once and that took me a while
to figure out.
\_ Ship it directly to China. That's where all the warm fuzzy feel
good "recycling" places are taking theirs.
\_ Throw it in da Bay.
\_ toss it in your neighbor's dumpster.
\_ oooh, good call. I wish I'd thought of that first.

6/27 Can anyone who has used Maxyma and Mathematica/Maple comment on
them? I am using mathematica and find it overhyped yet inconvenient
for the kind of symbolic manipulation I need. I need to implement
diverse kinds of say algebraic strctures and rules and to exert close
control over how the the rules are applied. That is I know how best
to simplify but want to use the program to do the bookkeeping. Ok tnx.
\- er do you actually have a copy of MACSYMA ... I'll buy you lunch if
if you actually have VAXIMA running on a VAX. Mathematica used to
be really unreliable. I havent followed discussion about it for a
few years and mostly use it do draw pictures or do pretty simple
things now [some factoring and computing some sums] ... I like
Maple6 and many colelagues use matlab. --psb
\_ Derivatives of DOE Macsyma is now GPLed, see e.g.
http://www.ma.utexas.edu/maxima.html and
http://sourceforge.net/projects/maxima and on GNU.
No I haven't tried to install. I want to have some confidence
that it will be useful before trying that.
\_ for symbolic math, Maple is great. matlab is only useful
if you have the symbolic math toolbox.
\_ what do you all mean by "symbolic math"? symbolic as opposed
to what? does this mean like modern/abstract algebra?
\_ for example:
symbolic: finding the indefinite integral (a symbolic
expression from another symbolic expression)
nonsymbolic: finding the value of a definite integral
(number-crunching)
\_ Anyone know of a good open source version of a program like
matlab or maple?

5/23 For those of you who missed the "commanding heights" on PBS, you can
actually watch the whole series online.
http://www.pbs.org/wgbh/commandingheights
I hope that all PBS shows are online in the near future.
\_ The url for the qt movies is:
http://www.pbs.org/media/commandingheights
Its pretty cool that PBS put the show on the web. I'd
like to see other PBS series on the web as well, starting
with American Experience and Nova and perhasp the recent
Evolution.
\_ From the "STORYLINE" link:
"For more than half a century the battle of ideas will rage. From
the totalitarian systems to the fascist states, ......"
What's the difference between totalitarianism and facism?
\_ Fascism is a form of totalitarianism with some additional
characteristics.
\_ cool... do we really still have any libertarians left?
\_ We never had any real libertarians.

5/8 Which class teaches you polynomial arithmetic?
\_ Math 32, remedial pre-calculus. Or did you mean the study of formal
polynomials? Then it's Math 113, some incarnations of 114, probably
parts of 250A, and 251. -alexf

5/7 Had this argument last week with a snobby co-worker of mine. He
argued that the diff algorithm isn't linear. Why isn't it linear?
\_ what a lame argument.
\_ try reading it. /usr/src/contrib/diff
\_ punch him in the nose and point and laugh as blood runs down his
face.
\_ This is the algorithm used (according to diff's own docs):
http://www.cs.arizona.edu/people/gene/PAPERS/diff.ps
As you can see from the abstract, the worst-case performance
is linear in the size of the file, but also dependent on the size
of the minimal diff, D, with O(ND) being the actual bound. Whether
that bound can be referred to as "linear" is a fuzzy question. Note
also that the average-case performance in a supposedly reasonable
model is O(N+D^2), which is "linear in N" by most people's
definition of the term. -alexf
\_ Fuck that. Punch him in the nose instead.

5/7 Say you have a matrix A, and they say that A * A^-1 = 1 (right?)
How does one get A^-1?
\_ you'd think if you were going to post some simple math question,
you would first read the replys to the previous one.
http://www.mathworld.com has the answeres to all of these questions,
with links to related questions, great examples, etc.
that should be your fist stop, not the motd.
\_ one takes math 54
\_ obviously A^1 is the same a 1/A.
\_ for a 2x2 matrix, it's trivial. for larger matrices, check out
a linear algebra reference for details. but for now:
(a b) ^-1 = M(d -b) where M = 1/(determinant)
(c d) (-c a)

5/3 If I want to learn about error correction, compression, and cryto,
which class would I take? crypto? _/
\_ Info theory at Stanford. Berkeley does not teach ugrad info theory.
\_ Information theory. Read Thomas & Cover. There is an information
theory class using that book at Stanford. Berkeley does not
teach information theory to undergrads.
\_ 170 talks about the basics of both, 150 has some error correction
too. specifics?
\_ Crypto classes: 261 (well, security), 276 (protocol-level), and this
semester Wagner taught a 294 which was block-cypher level. Even
though I've managed not to pay any attention to 174, I remember
somebody saying something about entropy, so likely has to do
something with compression and/or random number generation.
-chialea
\_ "managed not to pay any attention to 174". Okey dokey, now
who was making noise before about the best Cal ugrads not
getting into Cal grad school?
\_ Not best. Schmooziest. Big difference.
\_ if you were as good as chialea, wouldn't you be bored
by 174? --chialea #1 fan
\_ several EE courses discuss compression (the multimedial related
signal/image processing courses)
\_ depending on the prof, Math 114 often covers coding theory, and
error-correcting codes. - rory

4/26 Is it possible to find the median value of a group of numbers in O(N)?
\_ Yes, but in practice people use an O(n log n) solution. -op
\_ Yes; there is a fairly simple randomized algorithm which does this
with high probability, and a non-trivial deterministic algorithm
that people don't usually bother with. If N is really large, it's
probably worth your time to look into the former (see section
3.3 of Motwani&Raghavan, where it's called "LazySelect"; the
original paper is Floyd&Rivest, CACM 18:165-172, 1975, but it may
well be rather unreadable; M&R also gives refs for the deterministic
algorithms). -alexf
\_ you can sort numbers in O(n) with radix sort and counting sort.
\_ sorting is normally assumed to be O(n lg n)
\_ and your point is...?

4/34 Most databases use B-tree structure to store the data. Is there a
mathematical proof that this is the most efficient way to store
a dbase? Best in update times, delete times, record sizes, etc?
I'm wondering if there are better structures for specific structures.
Like a database full of numbers is different from a database of
words. thanks.
\_ Proving lower bounds on storage space of an arbitrary object is
undecidable (it reduces to finding the Kolmogorov complexity of
the said object). -- ilyas
\_ You meant "reduces from," of course... (the other direction does
not imply uncomputability; and there are other issues with
storage of arbitary data structures [e.g. efficiency of
later access]). -alexf
\_ Sorry, I wasn't using 'reduces' in the technical sense, I just
meant the two problems are equivalent, but yes. If I had a
terminating algorithm for proving lower bounds on storage
space I could use that algorithm to find the Kolmogorov
complexity of an object, which isn't possible. Interestingly
enough, some lower bounds on running time of data access exist
(O(log n)). -- ilyas
\_ Uh, the insert/delete/search bounds are well known and well
understood. STFW or read a databases book to find out and draw
your own conclusions. They are not by any means the best, but,
they are good for many of the more common operations that are done
on a database, and not too bad (TM) on the less common operations.
And the fact that you ask if the performance would be different for
a database of numbers vs. words shows a gross misunderstanding of
what the hell a database is.

4/17 for a while various heavy metal bands were hiding satanic shit
in their songs that can only be heard if you play the record
backwards. does anyone know of a metal song that displays
some satanic looking shit if you take the fourier transform of the
song? that would kick ass. i'm thinking of emailing Danzig to
suggest it.
\_ <DEAD>chaos.yerbox.org/face<DEAD> and
http://www.tp.spt.fi/~cleth/aphex.gif
\_ that kicks ass!@!!! thanks! now much time will be wasted
combing my metal mp3s.

4/10 What is the class to take to understand inner/outer product, vectors,
norm induced, orthogonality, etc?
\_ What you need to do is use your drug of choice while studying and
then use the same drug shortly before the exam so you'll be in the
the same state of mind and you'll be just fine.
\_ It was Math 54 in my day. (That day being the one after Math
50AB.) -geordan
\_ Math 50AB is gone... but 54 is still the one this guy's
looking for.
\_ Given that the op said "understand", the answer you probably are
looking for is 110. If you meant "understand well", the 250AB
series (B in particular) would probably be useful as well. Or
at least H110. 54, at least as taught by most profs these days,
is too focused on teaching basic computational skills to give
people a good feel for the concepts. -alexf
\_ i did not take 54 at cal, but my observation was that
it was taught in some way that just failed to work at all.
i asked reasonably smart people if they know what an eigenvec-
tor was after that class, and they had no clue. if you
want a lower division introduction to linear algebra or
vector calculus, go to a JC where they hire actual
teachers instead of mathematicians who are forced
to teach.
\_ Sorry but I learned what an eigenvector is the first time
Kahan explained it in class. What's wrong with you?
\_ Geeze. Eigenvector: x such that Ax = kx, where k
is the eigenvalue....
\_ What does it *really* mean, though? That was explained
to me first in Math 50B, although I already knew how
to compute eigenvalues from Math 50A (and even high
school). So, as always, YMMV. --dim
\_ What an eigenvector *really* means depends on the
matrix it comes from. I've taken both math 54 and
math 110, and true, they don't teach intuition. But
then again intuition is not something that can be
taught, but something acquired through application.
For a good introduction, which seems to be what
the poster is asking for, read "Linear Algebra and
its Applications" by Strang. If you want to see
linear algebra in action, take a computer vision
course (CS 280) or a course on semidefinite
programming/convex optimization (EE 227 I think).
Through all these courses, the important thing to
keep in mind is that linear algebra is a *framework*.
It's a compact way of representing a certain kind of
problems. Because this model is well-designed, there
are certain properties that has some meaning in real
life. Eigenvectors are an example. -- alice

4/9 i am working on modeling semiconductor devices and i need a
curve-fitting tool to generate mathematical model of the devices.
what are some of the free and commercial tools available? thanks.
\_ Get a book, copy the algorithms.
\_ excel works quite good. thx anyways. -op
\_ You can do curve fitting with neural nets -- a couple of lines of
C, and even fewer lines of matlab.
\_ just a couple lines, are neural nets that simple?
(don't know anything about them).
\_ sure, provided you have the right library.
\_ Libraries are for the weak.

4/4 Does anyone still have the url of the webpage about the infamous
Professor Wu of the math department? Thanks!
\- /tmp/hurricane_wu --psb
\_ http://www.google.com/search?hl=en&q=book+%2Bof+wu
\_ Thanks guys! You the best!
\_ oh the memories... I still can't believe I almost got a B-
--scotman
--scotsman

04/730 I forgot my calculus, please help me out. does the line integral of
a function f(x,y) compute the length of the function on top of that
line, or the area of the function above that line? (e.g. does the
line integral of a hemisphere calculate the length of the arc above
the line, or the area of the half-circle above the line?)
\_ i predict that you will be much more satisfied with the responses
to your question of you tell us *exactly* what the problem is.
\_ I did already, look in the parens.
\_ the "line integral of a hemisphere" makes no sense.
one takes the line integral of a *function* along a
*path*.
\_ a hemisphere is a function.
\_ a hemisphere is not a path. a half-circle
is perhaps what you're thinking of?
\_ You want a surface integral if you're integrating over a
surface.
\_ asking these type of questions on a sysadm infested forum will
get you nowhere
\_ i am not a sysadmin, and i have a math degree. it's justa
badly phrased question.
\_ ditto.
The MOTD: Not Just For Taos Monkeys Any More (tm)
\_ Isn't Taos dead?
\_ Taos Never Ended

3/17 What are some good schools that do quantum computing research?
\_ Stanford, Berkeley, MIT.
\_ Stanford only has Colin Williams and not much else. Berkeley
and MIT are probably the main hubs right now. There's also
Andrew Yao at Princeton, some people at Cambridge and Weissman
IIRC, and the rest are at Almaden and some of the national labs.
Why do you ask? Is there some particular flavor of quantum
you're interested in? -alexf
\_ interested in the abstraction and application layer (eg
simulator based on primitives defined by physicists, etc)
Got comments?
\_ Ehhh... Based on my rather limited understanding of
the field, it will be a decade or two before the
application and abstraction layer become relevant. The
application and abstraction layers become relevant. The
highest-level work that exists right now is using
physical primitives to get algorithmic primitives, and
even then the algorithmic primitives under consideration
are rather abstract and rarely of any practical value.
Also, quite a few people are working on lower bounds,
at an equally abstract level. Perhaps you may find
the following tutorial on quantum computing interesting:
http://xxx.lanl.gov/pdf/quant-ph/9809016
\_ I was unable to view this URL. Maybe another, or
perhaps I'm misunderstanding a cue in how you wrote it?
While written a few years ago, it is still showing the
state of the art insofar as the practical aspects
of quantum go. -alexf
\_ Shore's at AT&T Labs, too, but no one else. - chialea
\_ Lea, it's Shor, and there're other quantum people there,
including a few fairly well-known names (Sloane, Rains).
If I were you, I wouldn't make blanket statements such
as the above on a topic I haven't worked on much...-alexf
\_ Aww, cut the bitch some slack -- she hasn't finished
E190 yet, after all.
\_ Yet another anonymous behind-the-computer-screen
tough guy.
\_ why not? you do. :P -chialea
\_ Mmm? Explain? -alexf
\_ wow look at this great online rivalry.
\_ Seen better. Both are off the cuff, one
is arrogant off the charts, the other is
motd normal. The arrogance holier-than-
-thou thing has really been done. Very
boring.

1/21 What's the word on the various profs teaching math 110 this semester?
They are Kahan, Aschenbrenner, Pachter, Kantorovitz, Iliev, and
Wogoner. Obviously taking from Kahan is somewhere between suicide and
insanity (probably a little of each). What about the others?
\_ If someone ever tells you, "Prof. XYZ is really hard but you'll
learn a lot!" you should run, not walk to the nearest L&S advisor
to drop the class. Don't ever take a class with a Prof described
that way.
\- taken a class from Marina "you'll probably fail but she's one
\_ i thought all math profs were gay?
of the best teachers i had" Ratner?
\_ she told me "i think probably you will not get an A, but
don't worry." after i failed the first and second midterm.
she gave me an F. I rally am glad i took it though, since
i learned lots of set theory that i never would have learned
from the guy with the weird sore on his head.
\_ And now you have an F on your record and need to retake the
class. Good plan, not worrying and all that.
\_ WAgoner sucks hard.
\_ Wu sucks so bad, how come the math department never does
anything about it? Like firing his sorry ass.
\_ He's a minority. Can't do that. Look at the guy who was
giving secrets to the Chinese. Nothing happened because he
was screaming racism and the Clintonistas broke.
\_ The guy who everyone accused of being a spy wasn't
even Chinese. Last I checked, Taiwan was a pro-US
country. I'm not crying foul because it's racist.
I'm crying foul because, as usual on the motd, you
accuse people without actual proof but give the
bullshit excuse that "revealing evidence would
comprimise national security". Trial by McCarthyism
died decades ago.
\_ Say what? Since when does being from a province founded
by the losers of a civil war make you not of that race?
That's just fucking bizarre.
\_ I am Chinese and the math dept has my full support if
they want to fire his sorry ass.
\_ Chinese studying mathematic is not a minority group
for admission or faculty recruiting. The math dept
cares only for researches. If Wu got published
and recognized for research, he would not be fired.
You need to research more on how academic positions are
filled.
\_ Why?
\_ Pachter is cool in person, but is known for being somewhat tougher
than normal in upperdivs. Also generally considered a decent
teacher, I'm told. -alexf
\_ Wow... I thought it was just me. Although Kahan is no Wu...
\_ negative vote:
Kahan: ...
Wu: ......
Lam: ..
Ogus: ..............................
\_ I think fewer have tasted of the wrath of Kahan
\_ I survived the splintery broom handles of each. Kahan
was slightly less painful during the actual rape, but left
me much more bloody. Wu was an experience I would do best
to leave to the imagination. --scotsman
\- ObWu:http://www.jiggscasey.com/slappy/book_of_wu.html
BTW, it's kind of pecular that Wu takes teaching so
seriously. If you go to his homepage there are links
to papers he wrote on teaching math, ok tnx --psb
\_ this makes me curious. What are some of the
"inappropriate" exam questions he has raised
\_ I took Wu for math 104. He was as fair as anyone else,
never asked a trick question or a question that wasn't
unlike anything we hadn't seen in the homework.
THe fact is, he always rags on the math 1a and 1b students
for not trying to truly learn math, but just trying to get a
good score. He held extra unpaid tutoring hours once a week
after class, and cared very much about each student putting in
the effort to learn. He's not pretentious nor holier than thou
with his smarts, whereas Kahan is disliked universally across the
board for his rather arrogant behavior, this includes faculty.
The exam difference is that Kahan will give you questions that
distinguish the top 1% in a class whereas Wu (for upper div math)
\- i dont think kahan is arrogant. i think there are
cases where he probably thinks "i have been thinking about
this for 5years so no i dont really want your off the cuff
opinion." however i image many of you working in technical
fields have been in similar situations. in my experience
he does not say things without researching them and when
he calls people wrong he provides examples and doesnt
just say "i am kahan. you are wrong." i think kahan is
probably the most discussed prof in themotd, which is
kind of interesting. --psb
\_ He does have a rather selective memory though.
Have a 'discussion' about something with him, and
prove your point. Watch as he forgets this ever
took place and have the same 'discussion' over
and over with him every week.
\- he probably marked the conversation to be
garbage collected!
will give questions that distinguish who has been following all the
homework and are comfortable with the material. Also, everyone in
Wu's class pretty much thought he was awesome and brought the material
to life.
\_ maybe he's a better updder div professor than lower div
i doubt you'll find one math1a or 1b student who would
agree that Wu was 'totally awesome'
\_ I think too many of Berkeley professors
cater to the top 10% of students rather
than the other 90%. Kahan is just an
extreme case of a general problem. He
probably should just teach graduate level
classes.
\_ good way of looking at it. BTW,
there are 15 seats left in the
class that is truly Kahan's baby,
Math 128B, i.e. "I am the most
recognized badass in Numerical
Analysis today, and you're all
fucked." Anyone want to take it
with me?
\_ Heh, I know profs who call Kahan
funny names behind his back
\- kahan was considered kind of a oddball
in the dept for a long time but he's also
one of those profs who other profs in
candid moments will say "you know he's
really smart guy" ... i remember BH and
PNH both saying that about him. The rep
for being peculiar comes from stuff like
when the faculty was soliciting ideas
for "what would you do with a terabyte
of storage" [i think this was for the
sequoia 2000 proposal] and most profs
had various responses saying they could
use a few hundred gigs for this or that.
Then they asked Kahan and he says
something like "i need 1.3453245 TB to
compute <>"[i dont remember what it was
_/
103 1/21 What's the word on the various profs teaching math 110 this se
19 1/21 What's the difference between a resume and a CV?
5 1/22 http://Linuxrouter.com,org,net are not working. I need a crash course on
5 1/22 Hello, here is an interesting problem [harder than the canoe-bowl
2 1/22 A moment of silence for Peggy Lee who died from a heart attack in
he wanted to do but apparently he had
worked it out very carfully and everyone
else was kind of speechless]. i think
there was a almost collective "holy shit"
when he won the Turing Award. --psb
\_ imagine kahan teaching in grade school.
\_ fine they're smart people. But smart != good teacher

1/8 I am interested in handwriting recognition. In particular,
Chinese handwriting recognition. What are the relevant CS/EE fields?
What is a good grad school to go to for such things?
- person who finally found out what he is interested in, but
don't have much idea on how to pursue his interest.
\_ AI.
Berkeley, MIT, Stanford, CMU, UCLA, UIUC, UW, etc.
\_ Machine Learning and AI. -- CMU, Cornell, Berkeley, MIT, ...
Here's a link to code which recognizes faces (which is similar
to recognizing handwriting):
http://www-2.cs.cmu.edu/afs/cs.cmu.edu/user/mitchell/ftp/faces.html
\_ Thanks, what about some tier two schools? Are they worth
going? Or should I just find a job at the companies that
are implementing these things.
\_ Gradschool or not depends on where your interest lies.
If you want to work on developing algorithms on handwriting
recognition, then you should go to grad school (in machine
learning). If you're more interested in the engineering
and implementation aspect of the product, then work for
a company. Somewhere in between --> work as a developer
at a research lab. If you decide to go to grad school, then
first find a research AREA you're interested in. Going in
with a specific application in mind is not really good,
because 1) your interests will change, and 2) you may not
find a professor who's interested in EXACTLY the same
application. I would suggest you start by reading some
papers on handwriting recognition, and look at the homepages
of people who do ML, and pick your favorite people. Then
write those people a nice email and demonstrate you know
what you're talking about. If you still have a couple of
years to kill at Berkeley, then start by doing some research
in the area. I don't know why I'm even writing all this
down. You're probably not even going to read this far.
-- alice
\_ Thanks! That helps! You are a very nice person.
I think I am interested in the engineering and
implementation aspect. Does that rule out grad
school or can it still be useful?
\_ In that case, check out http://www.synaptics.com Apparently
they make (made) chinese handwriting recognition
products, according to John Platt's homepage.
http://research.microsoft.com/~jplatt
John, perhaps known in this crowd as the inventor of
ClearType, is smart and a nice guy. He may even answer
general inquiries from random people about about
Synaptics and handwriting recognition. And please,
don't call me nice. It gives people the wrong
impression. -- alice
implementation aspect. Does that rule out grad school
or can it still be useful?
\_ If you have further questions, be VERY nice and send
her an email. She might respond. Sending personal email
reduces the chance that you're just trolling or
interested in the hypothetical
\_ why not a Master's where you concentrate on learning
AI, and machine learning ideas, and maybe work on
a project on machine learning, then go to industry
afterwards? Another option is to take classes at
Stanford's SITN (if they have those courses there)
while working.
\_ Study Dvorak instead.
\_ Japanese Handwriting recognition demo:
http://ai.bpa.arizona.edu/go/mlir/japanesehandwriting.html

12/19 Why is EULER-PATH not as important as HAMPATH? (seriously, what is the
main diff between "edges only once" and "nodes only once")
\_ Euler path is a linear problem- O(V+E). Hamiltonian circuit is
NP-Complete, which means that it's at least as hard as
thousands of other problems. Produce a polynomial time
algorithm for Hamilton and you can crack nearly any public-key
cryptography system.
\_ isn't prime factorization NP-intermediate?
\_ So? All that means that you don't _have_ to solve Hampath
in polytime in order to solve factoring. If you _do_ solve
Hampath in polytime, this still gives you polytime factoring.
\_ what's the O(n) alg for EULER-PATH then?
\_ Find all nodes with odd degrees. If there's more than 2, halt
and return "impossible". Else, start at a node of odd degree
if there is one, and just keep going around while there're
edges from where you are which you haven't used yet. It's
fairly easy to prove that this will always find an Euler
path if one exists. -alexf
\_ Not true. Consider this graph: |_ _
/|_|
|
If you start at the top node, go down,
go right, then go diagonally down and
left you've cut yourself off from the
square at the right. But you can start
a new cycle that picks up that square,
then splice it into the other path. -ok
\_ I stand duely corrected. Apply the algorithm listed
above repeatedly to the graph, restarting at any point
which has unused edges coming out. You'll get a
collection of paths, of which all but at most 1 will
be cycles; you can then "merge" the cycles into the
path by just taking a "detour" around the cycle from
the point where the path touches said cycle. This should
still be linear. -alexf
\_ Duly.

12/4 If a DFA of M accepts all languages in L, then what exactly is
the "complement of L"? Isn't the complement of L everything that
M does not accept, which is an infinite set?
\_ Usually you phrase things as "a DFA M accepts the language L"
with the extraneous "in" and "of". The complement of L is
usually everything not in L which is what M does not accept
which can be an infinite set. This is not a problem. Consider
the language L = {} (e.g. L contanis only the empty string).
In this case L complement is all non-empty strings. It is
trivial to build a DFA to recognize L complement. -emin
\_ ok thx emin. I can prove that if a DFA M can accepts all L
in polynomial time, then ~L can also be accepted in polynomial
time. However, how do I prove/disprove that if a DFA M can
accept context free grammar, then ~M can accept all ~L?
\_ DFA's can't accept CFG's. Did you mean "PDA M"?
Take your method of converting M into ~M and prove that
it accepts the inverse language.
\_ Actually DFA's can accept any CFG which is also a
regular language. For example, the language L = {}
is both regular and context free. However, as you
point out, there exist CFG's which DFAs can not
recognize. To the original poster: I'm not quite
sure what question you are asking, but the following
information might be useful to you. CFGs are not
closed under complement. That is if L is a CFG then
~L need not be a CFG. -emin
\_ YOU KICK ASS -original poster taking CS GRE

11/28 http://unicoi.kennesaw.edu/~jbamford/greguide/gresample.html
Question 8, why isn't the answer C? 1/2 of a binary search (on
average) would be (log2 N) - 1, where N is the number of nodes in
a complete binary tree right? So C SHOULD be the answer. But for
some reason it is not. Help.
\_ you should send email to help@csua.berkeley.edu. maybe they
\_ you should send email to root@cory.eecs.berkeley.edu. maybe they
can help you there.
\_ please don't waste our time -kevinm

11/27 More on letters of rec: So it was generally agreed that prof >> TA,
but what if you take a class that is taught by someone who is
basically a post-doc? I guess that's just somewhere in between?
Also, how valuable is it to get letter from a non-tech (CS, Math, etc)
prof if you're applying to tech grad program?
\_ Between a post-doc who knows you well and can write highly of you
and a prof who doesn't care, pick the post-doc. Prestige is
important, but it will be meaningless if he/she cannot write
highly of you. The important thing, imo, is that the letter
makes the admission committee able to appreciate your achievement.
A letter from Patterson saying "he took my computer architecture
course and he graduated" is pretty much meaningless. If you already
have two excellent recommendations on your tech "achievement",
I'll go for a humanity/math letter.

11/27 Let's talk about ilyas' blue-eyed problem. Again. I still don't see
how the base case works. Assume 1 blue eyed person only. How would
that person know that he should commit suicide? Wouldn't the brown
eyed person think the same way and commit suicide? Think induction.
Tom's basis is flawed.
\_ The big problem with this whole thing is that it assumes that
all these people have taken math 55 and understood it.
\_ Please report to the food vats immediately.
\_ No. The key is that there exists at least one blue eyed person.
If only 1 blue eyed person exists, he will notice that as far
as he can tell, no one has blue eyes. Since at least one person
must have blue eyes, it must be him/her. So (s)he kills himself.
\_ Added to that, a brown eyed person would see that there is a
person with blue eyes, and would expect him/her to commit
suicide after the first day. And when (s)he does, the brown
eyed person concludes that that person was the only blue
eyed person in the town.
\_ Can you explain the case of three blue-eyed people, both for
blue and brown-eyed people. Won't everyone expect someone
else to commit suicide?
\_ Another way to explain it:
[someone else motd-mashed the first explanation]
For two blue-eyed ppl, a blue-eyed person would see one
blue-eyed person on the first day. At the end of the
second day, both blue-eyed people would kill
themselves.
For three blue-eyed ppl, a blue-eyed person would see
two blue-eyed people on the first day. He would see
them again on the second day. Assuming that there are
only two blue-eyed people total, they would kill
themselves at the end of the second day. But we are
saying that our given person is blue-eyed, and there
are three blue-eyed ppl. On the third day, this
blue-eyed person would STILL see two blue-eyed people.
At the end of the third day, all three blue-eyed people
conclude that there must be three blue-eyed people, and
they must be one of them, and kill themselves.
\_ Ah, ok, I finally get it. Thanx! -stupid Math 55 flunkie
For two blues and one brown, from a blue's point of view
there is one other blue and one brown. Now at the second
day, each blue knows he's a blue, because if he was brown
the other blue would have known he was the only blue since
there is at least one blue and the other two are brown.
So both blues kill themselves. From the brown's point of
view, he knows he's a brown by the third day, since the
blues wouldn't have killed themselves yet had he been blue.
--0x48
\_ Take math1a or 55 or high school math. learn induction. 0xAFB
\_ one of the many problems is with ilyas' question. He should add
that each person can see every other person ONCE PER DAY. This
question really reflects ilyas' intelligence.
\_ 1.) The kingdom was small: any person in the country could meet
all others in one day.
?
\_ it says 'could', but that doesn't mean it is necessarily so.
\_ Rule 1 suggests that they could if they wanted.
Rule 2 suggests that everyone really wants to.
The weakness perhaps is we have a lot of inferences.
\_ The weakness is that it's a stupid problem. -tom
\_ I thought the puzzle was a good one and I learned
some things. Of course, the problem did have
problems.

11/23 Can someone please tell me what textbook and/or author we used for:
math50a, math55, and stat134? I need it from 1993-1995. THANKS!
\_ let me guess, ypu're applying to MIT, right?
\_ let me guess, you're also applying to MIT, right? Or are you
already there? Help me out dude...
\_ I'm applying. And I'm a dudette, btw. -chialea
\_ where else are you applying to? Let's get together and
start a grad school application club!!!
\_ chialea, what'd you get on your subject & general?
\_ stfu ilyas
\_ It wasn't me, moron. I already know what she got.
-- ilyas
\_ bad things. especially the subject. and my GPA. -chialea
\_ 3.5 isn't bad considering the average GPA@Cal=2.3
you're off by a full half-point _/
ugh, you mean 2.8? 1.8? _/
it's around 2.8 _/
\_ Is that the average systemwide? how about for CS?
\_ _Discrete Mathematics and Its Applications_, Kenneth H. Rosen
(Math 55), don't know the rest. -geordan
\_ Math 50a is now Math 53, right? If so, Stewart's "Calculus:
Early Transcendentals" was probably used.
\_ no, 50a became 54. for math 50a in spring 1994, we used anton,
_elementary linear algebra_ and boyce & diprima, _elementary
differential equations and boundary value problems_. -lila
\_ THANK YOU SO MUCH LILA, you've been very helpful. By the way,
are these classes required for the "other" CS?
\_ no, just math1b and cs61a. i took math50a because i was
briefly under the delusion that i wanted to study physics,
and i took cs61b just for fun. -lila
\_ well? Did you really have a lot of fun?
\_ We used the same two books (different editions?) in Spring '97.

11/7 So, okay, I'm 1/2 way through math 55 and I don't see how relevant
it is to computer science. any comment? -clueless sophomore
\_ Take CS170 (and 172/174 if you have the time). You'll get a good
whiff of why 55 is vital to CS. Even 150/164/188 will rely on
snippets of it. -alexf
\_ Unless, of course, you take the class from Kahan. In which
case, none of the class will be relevant... to anything.
Unless, of course, you are a math prodigy. Then it will be
relevant to increasing your nerddom.
\_ Kahan will be teaching math 128B next semester, Im preparing
NOW FYI, anyone else taking it, be prepared to have backup
classes so you can drop this!
\_ I wish somebody told me this a few years ago. I am going
to go back to Berkeley to beat him up someday.
- screwed by kahan.
to go back to Berkeley to beat him up someday. "You are
stupid" was what he told a friend of mine who worked for
him. - screwed by kahan.
\_ Sit through it and hope you gain clue some day.
\_ realize that computer science is that to which math 55 is
relevant.
\_ Hm, good point.

11/7 I hate math 55. If CS is an extension of math 55, I'm gonna drop out.
\_ if you don't like math 55 you are better off doing something else
with your life. You will not be happy as a programmer.
\_ I don't think math55 is a good measure of what a career in cs
is like.
\_ career in CS or a career in programming? they are not the
same thing.
\_ *sigh*
\_ well, obviously if you just want to be a code monkey,
you don't need to be able to grok math55. hell, you
don't need to go to college either.
\_ What's your definition of a code monkey?
\_ me.want(obBanana);...
\_ well, if you have a million monkeys sitting in
front of a million terminals for a million years..
\_ You end up with many dead monkeys?
\_ UCB undergrad CS labs?
\_ Definitely, most CS majors have no pure theoretical interests,
they are looking for a well paying job; math 55 will definitely
help sharpen certain mental attributes, but most of CS is long
work at the lab and understanding of the theory in 170 series..
\_ false dichotomy: pure theoretical interest vs. looking for
well paying job. there are many cs research areas that are
not theory and some (not many) theory-type jobs that pay
well.
\_ Well, I think the really smart ones go out and get high
paying theory type jobs. The fact of the matter is that the
average CS graduate (undergrad) is not going to be the next
brilliant theory head, and will just want a good salary and
a good work enivironment. Oh yes, btw, I think you have to
be absolutely brilliant to do theory type jobs, I dont
think most people fall into that catgeory either.
\_ The really smart ones format their motd entries
correctly.
\_ there are certainly CS areas that don't need as much discrete
math, e.g. AI, information modelling, or networking even. but if
you hate continuous math (calculus, series, etc) too, then give
up now! any heavy CS requires a math strength _somewhere_..
\_ Um, graph theory is used pretty heavily in the above disciplines,
and Math 55 is a great introduction to graph theory.
\_ AI doesn't need discrete math? I see...
\_ Well... it depends how intelligent you want it to be.
\_ no, it doesn't. AI needs as much combinatorics, graph
theory, and numerics as any other aspect of CS. you're
deluded. if you don't understand math 55, you don't
understand algorithm. if you don't understand algorithm,
you're doing something else. and you certainly don't need
to know what they teach you in university to do those things.
\_ that was sarcasm, but thanks for the rant.
\_ I feel for ya. I hated Discrete Math as well (even though I didn't
take it at Cal). There're many things in life that won't require
Discrete Math and don't let that intimidate you from pursuing CS.
Besides (this is going to totally invite spam), you don't always
get to work in fields that you majored in. Most people would take
a job in fields that they're "trained" on; whether trained in
school, internship, etc. AFAIK, system administration doesn't
require Discrete Math. But at the same time, when you commit
yourself to CS at Berkeley, you're setting yourself up for research,
software/system development or teaching.

10/29 ssh cipher: blowfish or 3des... and why?
\_ 3des is more processor intensive. Blowfish is younger, but
theoretically superior because of some math that I don't
understand.
\_ Blowfish. Its faster than 3des and can support a longer key
length (448 bits vs 168 bits). There are no known exploitable
weaknesses in full Blowfish (Blowfish with reduced rounds is
exploitable).
\_ The key length difference between two _different_ algorithms
is irrelevant unless you have a thorough knowledge of the
actual keyspace _AND_ decryption complexity of each, which
we don't. -alexf
\_ Blowfish. It's faster and as (if not more secure) as far as
anyone knows. If you're securing stuff against a hostile gvt,
perhaps you should stick with something safer and slower, otherwise
don't kid yourself, blowfish is fine.
\_ "Make no mistake! We will crack it for surveillance purposes!"
\_ muahahahahh! your puny crypto will fall before our mighty
quantum computer! ...just give us another few decades.
-a physicist
\_ wouldn't this lead to an unbreakable cipher as well?
or is this only if you have a quantum comp also?
\_ Comrade, I am having zee unbreakable cipher. It
iz called ze one-time-pad. We have been uzink it
for years you unwashed american pig dog.

9/20 How do I pass a pointer to a member function in C++?
I'm trying to use mergesort (stdlib.h) like this
mergesort(array, arrLength, sizeof(int), intCompare);
where intCompare is my comparison function-- but I'd like to put
intCompare into a class. But
mergesort(array, arrLength, sizeof(int), MyClass::intCompare);
doesn't work. How do I do this?
\_ You can't.
\_ You can't because a member function is not quite a function in a
sense you are used to. You see, all member functions implicitly
assume a 'zeroth' argument, which is always the object on which
this member function is invoked. In general, you do not know the
identity of this object at compile time, and even if you did, there
is really no syntax in C++ to allow you to specify this information
in the function pointer type. What you want is to create a wrapper
function, which calls the member function on an appropriate object.
Then you can pass the pointer to the wrapper function to your
mergesort routine. It's worth noting that object oriented languages
with closures and curried functions, like ocaml, avoid this
problem altogether. -- ilyas

9/18 I never took 172 and don't have the Sipser book. What is a good
alternative?
\_ the files in <DEAD>www-inst/~cs172<DEAD> are protected. Does anyone
have the files where I can download them from? Thanks!
\_ Papadimitrou's book is very good. But Sipser's book is not
bad either -- just buy it. -- misha.
\_ in what respect is it better than Sipser? Papadimitrou has
two books, one is Elements of the Theory of Computation and
the other one is Computational Complexity. Which one are you
refering to?
\_ "To which are you referring?"
\_ "To which do you refer?"
\_ "What book is you tawkin' 'bout Huck?"
\_ A good alternative to not having this book is to buy this book...
or check it out of the library.
\_ Nerds usually like "hopcroft and ullman" it's sufficiently
status-generating.
\_ in what respect is it better than Sipser?

9/14 I'm trying to buy the 2nd edition of Intro to Algorithms from
mitpress, but they're telling me it can't be sold in the US. Does
anybody else know about this? They're not being overly helpful.
\_ nothing about it on the books pages on http://www.amazon.comlink:www.mitpress.com or http://theory.lcs.mit.edu/~clr
You sure they just didn't mean it's not printed yet?
\_ Cody's books has copies of the 2nd edition - twohey
\_ What's the difference between the two editions?
\_ Cody's Books has the 2nd edition in stock. -twohey

8/20 I'm having a hard time figuring out some of the math behind
diffe-hellman. The "key", pardon the pun, to the security of
dh seems to be is that calculating g**(x*y) mod n is hard
for an attacker. Say x and y are small, less than 1024,
couldn't an attacker just precompute all possible K (and K')
based on n and g and then do a table lookup based on the X
and Y values that are exchanged to get K (or K')?
It seems to me that you need to make x and y quite large to
have any sort of confidence that K and K' are secure. BUT,
a large x and y means the compute time per key exchange is
exteremely long. What are commonly used upper bounds on x
and y?
Sorry, if my questions are exteremely simple, I don't have
a good handle on this material yet.

8/2 What does "x (mod y)" in mathematics mean?
\_ how are you a computer science undergraduate without knowing this?
it's the remainder of x divided by y.
\_ Use the distributive property:
x (mod y) = (x mod) (x y)
Makes sense now?
\_ I still don't get it. What does the latter mean?
\_ Man, I was kidding. Sorry about that. Seriously,
though, "mod" just means the remainder, like from
elementary school. So for example, 4 mod 3 is 1.
\_ You are missing the minor technical distinction between
"x mod y" and "... (mod y)", see below. -alexf
\_ Well there was no way for me to tell he was referring
to FLT until he brought it up. That would have changed
my explanation.
\_ But that's not the theorem. It shouldn't be
an = sign, but rather a "congruent" symbol,
which is 3 horizontal lines. It'd take a
little too much time to explain, so I'd
pick up a Math 55 text for more details.
\_ Well there was no way for me to tell he was
referring to FLT until he brought it up. That
would have changed my explanation.
\_ You're not being blamed; your explanation is
reasonable given that you weren't specifically
asked for distinction between mod and (mod).
-alexf
\_ I just read about the Fermat's Little Theorem, which
states "Let p be a prime which does not divide the
integer a, then a^(p-1) = 1 (mod p)". I don't understand
what the "1 (mod p)" part means. Isn't "1 (mod p)" always
1 for all p greater than 1?
\_ "(mod p)" after an _comparative statement_ means that
that statement is checked only after taking the
remainders of both sides when divided by p. So, the
following two lines, e.g., are equivalent:
a=b (mod p)
a mod p = b mod p
(Note that to make the different meaning of the "="
clear, the "proper" way to write the first line uses
a 3-line "=" sign instead of the usual =). -alexf

7/16 I'm new to CSUA. Can somebody tell me who the following people are
(one sentence per user please thanks):
tjb- trevor j. buckingham. controversial republican that complains
about being oppressed and spouts lots of harsh remarks on newsgroups.
smokes a lot of pot and is into turntablism.
paolo- ???
tom- grouchy bike Nazi
kchang- ???
nweaver- (what is "I partied with nweaver?")
ilyas- russian guy who talks about physics and "AI" and "hard"
theoretical problems.
ali- arrogant Irani who knows C++ well. but no one cares.

7/10 AI is the stupidest movie I've ever seen. It insults my computer
science intelligence. Don't waste yer $ on it.
\_ stupider then The Net? that actually sounds kind of like an
impressive feat.
\_ I actually enjoyed it a lot, up until the the underwater Manhattan
scene. They could've and should've ended the movie there.
\_ Speaking of movies, go watch Memento, especially if you like
puzzles.
\_ Good for the first hour, so-so for the rest.
\_ The male-love-robot is funny. They should've made a female
version and a futuristic commercial for http://www.realdoll.com

6/20 Robotech DVD's released. Bad ass. Box set available with extra
disc featuring the Robotech pilot.
\_ fuck that! I'm waiting for the Macross DVD set with the REAL
voice actors and non of this "flower of Life" Carl Macek
bullshit.
\_ Fuck that, I'm waiting for Space Kitteers dvd's and Gaiking.
Gaiking Space Dragon on DVD would rock.
\_ I am Cyborganizer.
\_ cheapURLP
\_ #t
\_ Robotech? Bad Ass? Surely you jest.
\_ Yeah, it only created the giant fighting transforming robot
genre. (See, Transformers, Evangelion, to name a few).
\_ my ass it did. Maybe you forgot Mazinger Z? Of which
Voltes V was the sequel, and then on to Starbirds, and then
on to Dynamos... talking 70s here.
\_ Create the fighting transforming robot genre? Hardly.
Voltron for example was out many years before Robotech.
As I recall the same is true with Transformers. If Robotech
inspired the creation of the hideously bad Evangelion,
well that just another reason that it sucks.
\_ man Gundam was out before any of them. Stop watching dubbed
anime, and watch the "real" stuff.
\_ Quibble over semantics if you must. Macross (later
rebroadcast and munged together with two other series
as Robotech in the U.S.) predates Voltron, Transformers,
and Gundam. Get over it.
\_ uh, Macross originally was intended to PARODY the giant-
robot genre. there was plenty of giant-robot anime
well before Macross (Danguard Ace, Grandizer, Gaiking,
etc.).
\_ Robotech, Harmony Gold, and it's progeny must be destroyed.
Makurosu, ai oboeteimasuka, forever.

6/18 I have a question about diffie-hellman. After going through the initial
key exchange and generating the session key k', how do you use this key
with 3des or blowfish? Do you just trucate the key to the appropriate
length (doesn't seem right) or is there some other method? tia.
\_ Probably feed the key into a one way hash function (i.e. MD5) that
outputs the appropriate number of bits.
\_ This is correct. You would use a hash function. However, you
should not use Diffie-Hellman straight, much the same as you
should not use plain RSA. Get a cryptography book and read
about it.
\_ Okay, I understand the bit about the hash function, but
I don't understand why the session key k' can't be used
directly? I've been referring to Applied Cryptography,
but I can't seem to find a place where he explains why
the session keys should not be used directly.
\_ Here's a hand-wavy argument:
Your DH key must be larger than your 3DES key since
otherwise it's easy to break DH. This means that
you'll have to shrink your DH key to make your 3DES
key. You want to make your 3DES key by using all of
the randomness that you've got in your DH key, but
you don't know if truncating the DH key will do this.
However, you DO know that using a good hash function
to make your 3DES key will conserve all of the
randomness of your DH key.
\_ I guess I wasn't clear. I understand that I
need to hash the session key in a way that
preserves the randomness of the key and that
I need to use the hash value as the key for
my crypto algorithm.
The bit I don't understand is related to the
following: I keep reading that one should use
the hashed value of the session key *only* for
encrypting a different secret key and then that
encrypted secret key should be transmitted so
that all other transmissions are encrypted with
the secret key rather than the hash of the
session key.
Why can't I just keep using the hash of the
session key? It seems much simpler to do this
than to maintain a separate secret key.

6/17 [REPOST] Anyone know of a good introduction to the Gell-Mann
8 Fold Way that can be understood by a engineering grad (7
series plus one ud phyics class and one ud math class)?
\_ forget it.
\_ forget it. There's so much physics out there that is accesible
to someone with the background you describe, that will actually
teach you something useful about how the world works, and can
be applied to useful things like how devices work. why fuck
around with useless stuff you need grad level math and physics to
understand?
\_ Because it is interesting.
\_ No. AI is interesting.
\_ I've worked on AIs before (GA,NN,ES,FL) and IMHO
physics is much more interesting because it is
understandable via mathematics. AI is just a bunch
of weeny structured programmers whinning about
lisp, scheme, semantics, cognition, determinism,
etc without ever producing anything useful because
the concepts of intelligence and self-awareness
are too hard to reduce into programmable abstractions.
About the only promising avenue of research in AI
is machine learning, but once you get right down to
it, the most fancy machine we have today is about
as smart as a fungus or possibly a protozoan.
\_ You are a stupid, stupid troll, friend. You need to
read a real AI textbook. What you are whining about is
not AI, it's cognitive science.
\_ Pick up any intro abstract algebra or group theory text, read
up on basic group theory, read the stuff on SP/SU groups, and
then we talk.
From http://www.pickupguide.com
-*Warning*, DO NOT try and develop a relationship with a girl *before* you
sleep with her. Because, then your head gets all messed up, when they decide
they like that relationship they already got, and don't want to risk ruining
it by having sex.
\_ Why would you develop a relationship with her after you've slept with
her? Maybe it should be: "DO NOT try to develop a relationship with
a girl. Sleep with her as often as she'll allow until she stops putting
out." Seems like better advice that way.
\_ The age that I am, he's the reason I'm still single! These are
the guys who are out in the world.
\_ You are still single because you are a loser who blames sexually
satisfied people for your problems. Women can smell a loser a
mile away.
\_ Is that why they avoid me?
\_ Yes.

6/13 Long lived quantum entanglement of 2 macroscopic objects has been
achieved:
http://xxx.lanl.gov/abs/quant-ph/0106057
Food for thought. -- ilyas
\_ Thaumaturgy scheduled for teaching at UCB in year 2011
\_ We will teleport your gonads into the icy environs of deep space!
\_ Eh. Note that this has only been submitted to Nature and thus hasn't
passed peer review yet. The results they claim do sound impressive,
but I'm holding off on the party for time being (and I'm not nearly
enough of a physicist to evaluate actual procedure used and the
consequent claims' validity). -alexf
\_ .5 milli seconds is longlived? not useful for engineers yet..
\_ for quantum computation, that is wuite long. If you could
get that kind of lifetime for a 10,000 qubit system,
you would have a real quantum computer.
\_ Even 200-300 qubits at that speed should kick the crap out
of the current state of classical machines. -alexf
\_ 0.5 ms is long for all scientist/engineers.
\_ that's not what their sexual partners think.

4/24 "New-New Math":
http://dailynews.yahoo.com/h/ipts/20010423/cm/_new-new_math__1.html
American kids are so spoiled.
\_ In what way does it spoil a child to *not* teach them math when
they need it to do well in life? I think this is abuse.
\_ they have these adds on the radio where i live trying to
convince people that taking alot of math leads to great riches.
I keep thinking of the people i know who *really* know alot
of math, living on jolt and pop tarts and sleeping on
matresses in Evans hall.
\_ There's a difference between "most kids need math to do well"
and "needs lithium to do well".

4/17 Lookin' for something that can generate a dependency graph for
C's #include and Makefile's include. Thanks!
\_ Check out AST on freshmeat or sourceforge. It's out of AT&T
research.
\_ ast.pl is also good.
\_ make depend?

4/15 Anyone know anything about the profs teaching Math 110 in the Fall?
Specifically, Anshelevich, Givental, Harrison, Neu, and Pugh. Plus,
"The Staff".
\_ You should really wait till either Demmel or Kahan teaches 110
to take it.
\_ Harrison was the worst prof. I had at Berkeley. Avoid like the
plague.
\_ Pugh is very good, though he gives difficult exams.
\_ Is he related to "plugh", "xyzzy" or "say echo"?
\_ Both Givental and Pugh have a rather sizeable "hardcore" reputation
attached to them. Which, of course, may be good or bad, depending
on what you're looking for.
\_ "The Staff" is long and wooden. It's currently hidden in Wu's
office. On occasion, it is inserted up naughty students' recti for
maximal educational effect.
\- you know for the longest time i misparsed
this thinking it was a reference to prof.
wooden and some new prof long ... until i
remembered it was woodIN@math ...heh ...
speaking of H. Woodin, the tarski lectures
begin tomorrow on set theory foundations.
http://www.math.berkeley.edu/Tarski/2001tarski.html
\- I would take Pugh, i dont know Anshelevich. Pugh used to give
\- this guy seems to have a good
sense of humor.
"open problems" in 214, so he has his sick bastard side but he does
care about teaching. I would avoid his wife [Harrison]. ok tnx.
\_ hi psb! (note: psb supports this guy. once again, testament
to him being hardcore. it's up to you to decide whether this
is actually a good thing. which it may or may not be.)
\_ Only GPA matters.
\_ I can recommend Neu. Homework was difficult, lectures were
informative, and were tests not very hard at all.
informative, and tests were not very hard at all.
\_ I had Neu for 128A. I concur, although his tests weren't
exactly cake. They just seemed like it after the killer
homework. --dim

3/18 Exteremely intruguing paper (as seen on wall.log):
http://www.cs.umaine.edu/~chaitin/cmu.html
\_ snooze...
\_ take your philistine ass back to where you came from
\_ Yeah, get your ass back to High School, you aren't
mature enough to be in college yet.
\_ That algorithmic complexity/information theory stuff is
more religion than math or science. Godel and Turing's
results are far more practical, useful, and valuable.
\_ Advanced mathematics is just welfare the insane.
\_ "Chaitin's Omega:
* irrational number
* incompressible number
-- Oliver King
* all around fucked up number"
- Crow T. Robot
\_ Oh shit! It is now proven that we can't possibly prove
everything. (Seriously)
\_ So is it soon going to be deemed un-constitutional to ask our
troubled high school students to prove something in final exams?
(Just like how teachers are not allowed to teach Darwin's Theory
or Evolution, or something like that.)
\_ Huh? High school finals? It's all about feeling good. They
don't have to prove anything but that they've been properly
socialised and turned into good little robots.
\_ Intruguing? Paper? It was interesting, yes, but hardly
Intruguing. It wasn't a paper. It was a lecture.
\_ Okay, I got the paper part wrong.
\_ I think that people who are underwhelmed by this do not
understand the consequences of "maximally unknowable"
within the context of a proof system.

2/8 I have 20 positive numbers and five desired totals (all floating point
numbers). I need to pick five mutually exclusive sets (not necessarily
exhausive) of numbers from the 20 numbers, and then sum up the numbers
in the five sets to get five totals. My goal is to minimize the
mean-of-squares of the differences between the five totals and the five
desired totals. I wrote a C program to do the brute-force try-all-
combinations method (that's (5+1)^20 combinations), and it looks like
it's going to need ~120 years of CPU time on my P-II 350MHz! Is there
any better algorithm for doing this kind of things? Thanks. -- yuen
\_ why isn't it 20!/(20-5)! ?
\_ This is known as a 'bin packing problem.' It is NP-hard (in other
words it is at least as hard as any problem in NP). -- ilyas
\_ exclusive means (20! / (5! * (20-5)!)) right?
\_ No, that would be the # of combinations to pick one set of five
numbers from the 20 numbers. But in my case I need to pick five
exclusive (ie. non-overlapping) sets instead of one, and each
set can contain anywhere from zero to 20 numbers. -- yuen
\_ Can you use an approximate solution? I think of this problem
as being more similar to integer programming. It's equivalent
to min_A ||Ax-b||^2, such that 1^T A <= 1, where x is your
vector of 20 positive numbers, b is the five desired sum, and
A is a 5x20 matrix with the entries constrained to be either
zero or 1. You won't be able to reach the exact global optimum
in poly time, but perhaps you can try adding an L_1 constraint
to the objective? i.e.
min_A ||Ax-b||^2 + lambda*sum_ij |A_ij|, s.t. 1^T A <= 1
L_1 penalty punishes any non-zero values, so A will have as
many non-zero values as possible. Of course you're still
left with the problem of deciding which entries of A to clamp
to 1... Uh, need more optimization fu. -- alice
\_ If my memory serves me right, LP relaxation isn't all that great
for bin-packing. The first reference point to check would be
_Approximation_Algorithms_For_NP-Hard_Problems_, edited by Dorit
Hochbaum:
http://www.ieor.berkeley.edu/~hochbaum/html/book-aanp.html
It should be available at any university library by now. Chapter
2, written by Coffman, Garey, and Johnson (yes, THOSE Garey and
Johnson), is "Approximation Algorithms for Bin Packing: A Survey"
-alexf
\_ I'm not up to date with NP approximation algorithms,
but LP might be the easiest (and most practical) to
implement than more complicated methods. BTW, one can
express 0/1 constraints using (2A_ij-1)^2 = 1. The
problem then is no longer LP, but you can get a lower
bound using Lagrange relaxation (i.e. switching min & max),
then use gradient descent or something on the lower bound
function, which is usually much more tame than the original
problem. This all sounds very complicated but is actually
doable. I just don't know how good the approximation is.
Maybe the book will say something about it. -- alice
\_ Thanks for all the suggestions. Understanding what you
all said is already hard enough. Gotta refresh my
170-series knowledge first before I go from here. -- yuen
\_ can you think of a useful lower bound for what you're
suggesting? you are talking about lower bounding
|Ax-b|^2 + l*(|2A-1|^2-1) right? I'd bet that your
regularization term smooths out the surface so much
that you could just solve this using gradient descent.
that you could just solve this using newton raphson.
\_ this is one smart broad.

1/2 I've been getting the following error message repeatedly lately.
The authenticity of host 'quasar.cs.berkeley.edu' can't be established.
RSA key fingerprint is 14:1f:b3:63:83:6a:fe:73:4e:fa:64:30:9c:9f:c3:c8.
Is this a problem w/ quasar or is it the soda ssh client? Why doesn't
it allow me to add quasar to my list of trusted hosts?

12/22 Is the math instructor "Hurricane" Wu mentioned below the same
as the famed but controversial human right activist Harry (Hongda) Wu?
I heard the latter once was at Berkeley.
\_ yes
\_ no
\_ No. Prof. Wu from the math dept. isn't human and therefore has
no interest in human rights.
\_ Harry aka Hurricane used to work at Los Alamos until he was fired
for mishandling his tapes.
\_ Same Wu? The Joy of Lecturing by H. Wu
http://www.math.berkeley.edu/~wu/lecture.pdf
\_ The last man on the planet to write about better teaching.

12/21 Turns out that I got a lower grade than I expected. If enough people
in the class ask for a recount (all the grades), will it help? Has it
ever happened before?
\_ This doesn't fall under the jurisdiction of the Florida Supreme
Court, but then again, that never stopped them before. Go for it!
Every grade must count! Count all the grades! Even the smudge you
made on the paper in the place where the correct answer might have
been implies you had "student-intent" to fill in the correct answer.
\_ i had a teacher in hs who used to drink wine while he was grading
and get really wasted. sometimes he would only grade half the
exam and you would get a 20 out of 100 or something, and demand
a recount and get a 90. suprisingly, he was a really good
teacher otherwise.
\_ Just don't let the professor stall till the grades are
certified as final.
\_ Grades may only be changed to correct errors, not because the
\_ You can also file an appeal to a grade with some dept. at Cal.
It doesn't only have to do with errors.
professors grading scale was too high. (However, if the prof
consistently gives too many bad grades, he will get in trouble
eventually - see the case of Prof. Wu & Math 1A/1B in the early
90's.)
\_ yah, that foolio got fucked up. He's now been demoted
really awful in math.
\_ are those errors as in "Ooops, I read that 3 as a 5 and
misgraded you" or as in "Oh, I guess you answer is correct
mine (prof's) is wrong"
\_ I remember a horde of people dropping math 1a from wu in 91
\_ I had Wu and I think I got a B. What was his deal?
\- this is pretty funny ... --psb
http://www.jiggscasey.com/slappy/book_of_wu.html
\_ excellent linkage, thanks psb. READ THIS people.
\_ it isn't *that* funny
\_ Yeah, did something happen to Prof. "Hurricane" Wu?
\_ As I recall, he was still allowed to teach but was no longer
allowed to have any part in the grading process including
setting the standards, creating the curve, grade appeals,
etc. That was all given to his head TA. Me? I was there
for 10 minutes of lecture 1 and walked out. I knew what I
was looking at. This was while he was still allowed to
destroy hapless freshies. Any survivors from Prof Shang's
math 1b class still around? Oscillating circles.

12/14 I totally don't see any relevance in teaching Lambda calculus in an
undergrad course to describe stupid semantic rules. Fuck Aiken and
his stupid ambiguous exams!!!
researcher)
\_ usually to emphasize its distinction from an algebra. keep
in mind that "the calculus" taught in high school is
really "the calculus of infinitesimals."
\_ this is a simple question but: why do they call Lambda calculus
"calculus"?
\_ It's a way of calculating stuff. and it sounds cool (to a
researcher)
\_ usually to emphasize its distinction from an algebra. keep
in mind that "the calculus" taught in high school is
really "the calculus of infinitesimals."
\_ I actually wish Hilfinger covered some of that stuff.
\_ Hellfinger just asked you completely unrelated questions
pertaining to English lit or what happened on a certain
date in France that never existed. Often times those
answers were as simple as zero or nothing. Nevertheless,
I enjoyed pushing the very limits of my parasympathetic
nervous system.
\_ About dates that never existed? Then the answer is pretty
obvious: nothing.
\_ Has a Hellfinger exam question list been compiled?
I know two: one about some british poem and another
about some Spanish/Mexican revolutionary figure.
And i think it was french lit and english date.
\_ "someone" should definately do this... I remember two:
what was the HMS Java? I don't remember the answer
but can look it up. The other was a line from "Ode on
a Grecian Ern". If more people post them, I can
compile the list.
\_ this is a good idea. A question from one of my exams was
"Where do the poppies blow, between the crosses, row on
row?" (A: In Flanders Field)
\_ If you're going to teach language semantics,
at all, there are two ways to do it. (a) Operational
semantics, in which your language description is written
in something that works like Tcl. This is icky and went
out of vogue in the 70s. (b) Denotational semantics,
in which your language description is written in something
that works like Scheme (the Lambda calculus). Thank
God that your undergrad compiler class is not about stupid
shit like how to write a lexical analyzer, like mine was.
Also, http://m-w.com's definition of "calculus":
1 a : a method of computation or calculation in
a special notation (as of logic or symbolic logic)
If semantic rules are stupid, then what exactly is a
programming language? -blojo
\_ Programming languages are hard. Let's go shopping!
\_ lexical analyzers are not "stupid shit".
especially the practical applications of 172 stuff.
and neither are lambda calculus or type systems.
how can you justify asserting that they are? this whole
thread is just bizarre.
\_ well, they're kind of over-kill in general when all
you really need is an s-expr reader.
\_ How quaint; how '50s. Dude, humans were not made to
read s-expressions.
\_ I wasn't made. I was born. -human
\_ A lexical analyzer is a necessary component of a compiler
and it's worth maybe spending a week talking about them.
It is NOT worth spending 1/3 to 1/2 a semester talking
about them and doing major projects regarding them.
Any programmer with a clue can write a lexical analyzer.
It just takes general programming knowledge. The important
knowledge in compilers, the domain-specific stuff that the
class should be spent teaching, is all about semantic
analysis, code motion, and maybe provability. -blojo
\_ Um. I can write a lexer very quickly with automated tools
like Lex. Very quickly == hours, not days.
\_ Yeah, that's like my point, see. -blojo
\_ lexical analysers are good for building language -> machine
translators, but the underlying theory is useful as a basic
model of computation. knowing all the DFA, NFA, REGEXP
equivalence shit is really useful if you do CS.
also, there is a lot of theory that goes behind building
YACC. you could either use YACC as a customer (as in the
way compiler writers do) or you could delve into the theory,
like the way language people do. i think you're a lazy
bitch if you think this shit is bunk. -ali
\_ Bunk! Bunk!

4/249 I'm interested in tree-pattern matching algorithms. I'd like to
implement a language independent, synthesized and inherited abstract
syntax tree comparitor. Where is a good place to start?
\_ well, I actually am looking into the same stuff, this work
can do fuzzy tree matching, giving you replacements, renaming,
insertions, etc. http://www.cis.njit.edu/~discdb/treematcher.html
\_ probably not here.
\_ http://www.google.com/search?q=tree+pattern+matching+algorithms
\_ Check out the XML tree diff from IBM. Not sure if there is code
in PD, but they at least quote source references. < O(n^4)

10/20 Except for Graphics, it seems like high level math doesn't seem to
be needed in computer science.
\_ heh heh. heh heh heh. heh.
\_ yes.
\_ except for graphics and for anything that involves fucking
modeling. -ali
\_ well there's that whole crypto thing...
\_ I want to fuck a model. Does that require high level math?
\_ no. - paolo.
\_ in fact, having high-level math would probably hurt
your chances.
\_ yes. -math alum
\_ this is bullshit. it's true that math major can't score,
but well positioned math skills always help you score.
chicks dig guys who do math. it completes them.
it's a well known fact. -ali.
\_ if you include abstract algebra, then it is a big help in
compiler implementation, language design, AI language processing...
if you include topology and/or graph theory, then it is useful
all over the place. there are more examples but the motd
isn't big enough.
\_ Abstract algebra for 'AI language processing'? Where are you
pulling this shit out of? Idiot. Go learn AI.
\_ The motd is infinite!!!

8/15 Breakthrough in quantum computers!
http://biz.yahoo.com/rf/000815/n15481726.html
\_ Fixed the link.
\_ So it can solve a particular problem in one step instead of four.
Isn't that the result of a change in algorithm instead of a change
in the underlying electronics? How does switching to using atoms to
implement the logic make it possible?
\_ No, it is a change in the underlying electronics. Quantum
algorithms can't be done on non-quantum computers. - mikeym
\_ The fact that they successfully demoed this essentially confirms
that it is indeed physically plausible to implement the Quantum
Fourier Transform, which is at the heart of, among other things,
Shor's poly-time quantum integer factoring algorithm. Presumably
what poly-time factoring will do to computing needn't be
explained. Here's some reading for details:
http://www.cs.berkeley.edu/~vazirani/qc.htmlhttp://xxx.lanl.gov/ps/quant-ph/9809016
-alexf
\_ dude, I work in the industry, I don't understand this
crap. Should I go back to school?
\_ if you wanna work for peanuts as an academia phreak, YES
\_ if you want to understand it and/or contribute to it,
YES. if you don't, don't bother. it's rather unlikely
that there'll be practical industry demand for quantum
coders before you retire (or at least are too old to
pick up an entirely new paradigm).
\_ just wait for phillip's QC API --oj
\_ Too old? Like, his brain would seize up and he'd be
incapable of learning something new? All his bits
are in use? Unlikely.
\_ When you're 60, you will, in all likelihood, not be
to willing to learn a whole new world from scratch
\_ http://www.sciam.com/1998/0698issue/0698gershenfeld.html
This is a Sci Am article on the topic. For people who
haven't had Quantum Electro Dynamics in college (which is
like 99.999% of the world. :-)
\_ See second link above (LANL); it's perfectly accessible
for anyone smart enough to log in to soda and read the motd
(ie not that smart).
\_ hey1! :-(

8/13 Is there such a thing as an algorithm that can output another
algorithm? Kind of like self tuning, self evolving algorithm?
\_ Yes. Not as glamorous as it sounds; see also: genetic algorithms,
Remez algorithms, data-directed programming
\_ bison, yacc, (f)lex, and many many more. not self tuning though.
\_ There are algorithmns that can learn from data. It's really not
as sexy as some people seem to think, just an application of
statistics.
\_ self-propagating neural networks
\_ Neural nets are data structures not algorithms. And
there is no such thing as a self-propagating neural net.
There are neural nets with feedback loops, but they don't
output 'another algorithm.' They have some uses in time
\_ Tell us of the stars....
series prediction. Please don't be an idiot, read Russell's
book or something.
\_"A neural network is a processing device, either an algorithm
or actual hardware, whose design was motivated by the design and
functioning of human brains and components thereof" from the NN
FAQ. And I believe it is theoretically possible for a NN to
output another algorithm. Sign your posts. williamc
\_ A NN FAQ is not an AI authority. For one, this "FAQ" seems
to imply that an algorithm is a processing device, which
is idiotic. And a neural network cannot 'theoretically'
output an algorithm. It outputs an array or list of
floating point numbers. I recommend Christopher Bishop's
neural networks book as an excellent way of learning more.
\_ It's easier to babble on the motd and toss buzzwords
around.
\_ how dare you call me a "data structure". -brain
\_ feedback loops
\_ Does self-modifying code count?
\_ Optimising compilers fit, too...
\_ and my thesis!

7/28 Rest In Peace, John Tukey
\_ I don't know who this guy is, but doesn't he deserve the bits
required to spell out RIP?
\-John Tukey was one of the most important mathematical statisticians
"ever" ... spent a long career at Princeton. Long list of results
and many many important collaborations in many fields. First rank
giant in 20th cent mathematics. --psb
\_ He was one of the people who rediscovered the
Fast Fourier Transform algorithm and popularized it's
use in Digital Signal Processing.
\_ that's nice, but did he join a startup? Did he get XXXX
options? Is he a millionaire? I am not a rocket scientist
but I know how to invest and work at the right place. I'm
a twentysomething multi-millionaire already. Success is
measured by your $, not that IQ or humanity bullshit.
Fuck academia. Industry rewls. -industry pimp
\_ Twit imposing their personal morals on others removed. My
personal morals involve censoring others when I feel what
they said was distateful to me just because I can, just
the same as you've done. Let's hear it for more censorship
in academia.

7/17 What is the operating principle behind Computer Associate's "Neugents"
and why is it so damn smart?
\_ they took a neural imprint of ted nugent
\_ It's all marketspeak. They are using straightforward neural
networks, a technology that has been available since the late 60s.
-- ilyas
\_ No no no no no, the commercial said their new technology
was so smart computers can think!!!!!!!
\_ Yes yes yes!!! It's just like that computer 'HAL'
on 2001! "Dave, what are you doing?/" Ohmigod!!!

7/17 i think micro$oft's new language should be called C-
to match the grade i got in cs164 -- Social-Science Major
\_ WTF were you taking cs164 for as a fuzzy major?
\_ To take space away from an EECS major? BTW I didnt
really get a C-, but it's a better post that way.
The major is only fuzzy because Math, CS and Bio havent
figured it out yet.
\_ Anything that needs to add the word "Science" to it's
description probably isn't. Yes, including computer
science. -cognitive science alum
\_ Amen to that. Computer science is either math or
engineering, depending on which side you're on. And
cognitive science, is, of course, bullshit.
\_ No, Cog Sci is either linguistics or neuro anatomy.
Don't judge it from the cogsci 5 course you took.
-cog sci alum
\_ I am judging from CogSci100, CogSci101, and
CogSci110 courses I took. Linguistics is
all seem to warship at berkeley?
either bullshit or linguistics. 110/115 series
or the 130's. Neuro anatomy is neuro anatomy
and those who call it cogsci are simply trying
to cover the rest of cogsci's bare ass.
-- original poster
\_ oh, yeah? which of those is the idioitic
arguments of that anti-AI crusader who you
all seem to worship at berkeley?
\_ Wow, and this wasn't even me. -- ilyas
\_ I don't "warship" John Searle. He's a
pompous arrogant ass who has nothing to do
with anything. -cog sci alum
\_ I don't like John Searle NOR George Lakoff,
and yet I loved being CogSci at CAL. - Marco
\_ At least Lakoff wasn't an asshole
like Searle even if you don't like
his lecture materials. What'd you
not like about him?
\_ warship? We have a warship? Let's put our
football team on it and sail to Palo Alto.
\_ We have a speeling disfunkshun.

6/30 Now that the human genome appears to be all but decoded. Is
there any method to measure the number of bits that are encoded
in the genome. IE how does it compare to a modern operating system.
\_ Well, the encoding system is using a power of two, so there is
a very easy conversion. The problem is that it's not always
easy to see where code ends and garbage begins in DNA.
\_ ONE HUMAN ~ 4 TERABYTES
\_ Uh, I don't have my biochem text with me (on vacation),
but I seem to recall the human genome being 2,000,000 kbp
(kilobase pairs), or 4 Gbits of data (2 bits/bp). -nweaver
\_ That's just the program text. The Interesting Question(tm)
is How much does it take at runtime?
\_ The number is actually much less than that, since the
bitstring is EXTREMELY structured. Which means less bits. If
I were to guess, you're off by a factor of 100-1000. Maybe
worse. That doesn't mean anything however, since we know next
to nothing about the structure, and won't for quite a while
\_ ONE HUMAN ~ 4 TERABYTES NO COMPRESSION, PUNY HUMAN
\_ once the genome is there, the interesting stuff begins. For the
next 30-50 years, I think scientists will be working on the grand
\_ try 300-500; popular press is just listening to what the
funding proposals are babbling; anyone actually writing
them makes sure the timespan predicted is long enough
"so that i won't be around to be held responsible" but
short enough as to not to discourage investment. sad,
but true.
unification theory of DNA. A physical/biology/mathetical model
of the interaction of the different genes. Imagine running a
simulation of a new lifeform created by artifically pieceing
different genes! The complexity of such a simulation is beyond
anything we've done. Today's supercomputers used to simulate
nuclear explosions will look like toys next to computers
simulating artificial lifeforms. Who wants to guess on the
computational power needed to run a simulation of a single cell?
\_This is the typical clueless CompSci answer to biochemical
problems. I remember once one of my advisors said that the
problem with working with computer scientists on biological
simulation in actual living cells. Just pick your favority
problems was that they just didn't get it. I guess he had a
point. Why waste your time trying simulate a complete cell at
such a granular level on a computer? We can simply run the
simulation in actual living cells.
\_ Why bother running simulations of rockets, and atomic
bombs? Oh yeah, that's right, if you find something
*really* interesting, **THOUSANDS/MILLIONS** OF PEOPLE
**DIE**.
Apparrently, its true that those who can't do, teach.
\_ What are you trying to say? This makes no sense.
Just pick your favorite
organism and transform them. DNA is cheap and plentiful to
reproduce with a little lambda phage, plasmid, and PCR. Also,
simulation of a single cell, albeit interesting, isn't exactly
\_ >80 column idiocy fixed. Get a clue. -tom
completely useful. Since we are mainly interested in
multicellular organisms, a simulation of intercellular
interactions would be much more valuable. i.e. what exactly is
involved in the complex interaction of cell signalling during
embryonic growth, and how that interrelates to differentiated
cells. A more realistic goal is to use pattern recognition
techniques to be able to predict tertiary/quarternary structure
of proteins and enzymes from DNA, and probably one which is much
more profitable than trying to simulate organisms when the
actual organisms can be produced cheaply. Go buy yourself a copy
of Maniatis. -williamc.
\_ If you take a pure scientific view, there is lots of value
to understanding how cellular processes work, and being able
to model them means a huge step toward fully understanding
the schemes (algorithms if you will) nature has come up with.
From a practical viewpoint, you want to be able to model
a cell so you can design your own cellular signalling pathways
What you're saying, William, is that there is no value in
understanding the inner working of cells, that nuclear
transport, mRNA regulation, vessicle trafficking is not impt.
Thats a very narrow minded view.
\_ What he's saying is that full simulation is infeasible,
and suggesting a viable alternative. Get a clue.
\_ see below
\_ More than Moore's law can produce for you even if it lasts
through 2500 A.D.. Without a new computational paradigm, or a
better abstraction than sheer chemistry, this will not be
practical (in all likelihood) until well past the predicted
lifespan of the Homo sapiens species, or even genus Homo.
\_ Dude. Do you realize how LARGE the number
current_computational_speeds * 2 ^ (500 / 1.5) is?
\_ Yes I do. Do you realize that modeling a physical
system on quantum level is considered non-polytime on
a classical computer? And do you realize how many atoms
a cell contains?
\_ In something like 8 iterations of Moore's Law
(12 years) you'll be able to read 4 terabytes
(the DNA sequence) into RAM. The rest of the
cell structure is simple relative to DNA and
doesn't need to be fully modeled. By the time
you can read DNA into RAM, processors will be
running at 256 Ghz, with who knows how many
instructions per cycle. That's far more
processing power than a cell has. The only
computational barrier at that point will be
writing the code to model it correctly; that's
hard for a cell and much harder for a full
organism. -tom
\_ "The rest of the cell structure is simple
relative to DNA"? Get a clue, cs boy. You
can read the damn bytes into RAM, but you won't
know what the fuck to do with them. Predicting
"everything" from DNA, or even a small subset
of it such as the general protein problem
(folding, interaction, binding sites, etc), may
easily, to the best of mankind's current
knowledge, turn out to be, oh, say,
EXPSPACE-hard. All your Moore's law ramblings
aren't worth crap until we know SOME fully
encapsulated localization structure in the
problem (be it DNA, protein, life, etc). Which
doesn't seem too plausible.
\_ It would be stupid and _unnecessary_ to model the
individual atoms to model a cell or dna. For example,
weather modeling gets better everyday and they're
certainly not modeling every atom in a storm.
\_ See above.
\_ And do you honestly think we'll still be computing on
silicon then?
\_ The above was predicated on "no change of paradigm"
\_ But can distributed computer help, like what SETI@home does?
-- yuen
\_ Probably not; seti@home relies on the fact that an
arbitrarily large amount of computation can be done by
any node without needing input from any other ongoing
calculations; a cellular model would be much more
interactive. Still, I think the assertion that we'll
never have enough computing power to model a cell is
silly and unfounded. -tom
\_ 3 words for you -- "think avogadro's number"
\_ "No one would ever need more than 640k".
\_ I have to agree with william. You don't start a
computationally intensive calculation at the lowest
possible level of understanding. For instance, if you
ever want to see a result, you would not start a model
of even a modest polypeptide by doing ab intitio
calculations on the interactions between individual
electrons and nuclei. Modeling an entire cell based on
molecular interactions is similarly too complex and
really unnecessary.
\_I dont understand this fixation with atoms. You dont
need to model atoms, just the kinetics and thermodynamics
of interactions. Duh, anyone thats knows anything knows
theyre not going to figure out interactions in the cell
from scratch. We have 100+ years of abstraction to work
with.
\_ Nobody is talking about simulating cells at the atomic
level, dumbass. As for "why not try it on a real cell?"
It's a stupid question. It's always more economical to
simulate something first rather than try it first. You
can change your simulation parameters faster than you can
change your real-world experiment.
\_ this is utterly false. -tom
\_ this is the first intelligent thing you've
said in this thread, tom
How do you think we
build cars and airplains and computers? We break it down
into components, build models in computers, simulate them,
and then build small scale models. Drugs can be synthesized
in a computer faster than in real life. I'd love to see
how a particular drug will affect a cell even before
the drug exit in real life. Science fiction? maybe. But
then again, who would have thought of the internet 100
years ago?
\_ what is human gnome, and is it better than kde?
\_ alot of you missed a point made above, DNA isn't enough! The cell
itself carries much info that isn't in the DNA (via already synthed
proteins, sugars, biochemical microenvironents, mitochondria and
their DNA, imprinting (which the genome project is ignoring), as
well as other molecules that we probably don't realize are
necessary in a model). Yes, much will be able to be done, but the
necessary in a model).
\_ the total amount of cell information not contained in DNA
is almost certainly less than the amount of information
contained in the DNA. So call it 8 terabytes and 13
iterations of Moore's Law. -tom
Yes, much will be able to be done, but the
system will have holes and leave a lot to interpretation. That's
not to say that phages, bacterial sims, YACS, . . . are the answer,
they also have many, many flaws, but we are getting closer. And
it is probably the marriage of the techniques that will produce
the answers we are stiving for, with the great aid of human
intuition and analytical skills.
Anyhow, the 4TB, GB, whatever, of DNA isn't enough. Just
imprinting alone would add 2 bits to every base pair (methylated or
glycosylated), now add on everything else you forgot to consider.
Oh, and don't forget you need the environments of all surrounding
systems, i.e. in birth you need the mother, her DNA, and so forth
to get it all right. Bottom line, an approximation is better than
nothing, but don't get your hopes up too high!
\_ The first challenge is simulating an amoeba. -tom

6/18 What's the course number of the linear algebra class you need
for cs 180 (the computer graphics class)? How hard is it
to understand...old eecs alumni tell me it was quite nasty?
-- no clue
\_ Probably Math 54. It's fairly easy if you pay any attention at
all (unlike me). Take.. I think.. Borchards if you can. He gives
_really_ easy tests. --dbushong
\_ i thought math 50a was pretty hard. i don't think they explained
the concepts well at all. it wasn't until 50b that i started
understanding what was going on.

6/3 Thank goodness, somebody finally nuked that whole convolution
proof thread. Please keep that shit at a math newsgroup and
NOT on the motd.
\_ I would rather hear about a good proof than about most of the
other shit regularly discussed here. -- ilyas
\_ Tell us of the stars, ilyas....
please lick my hairy scrotum during a prolonged stint during which
\_ dear mr. "i would like to hear more about dating vapid playboy
bunnies",
please lick my hairy scrotum afetr a prolonged stint during which
i have not had a chance to shower.
Sincerely,
Ali.
\_ You have a scrotum?
\_ you would have licked it sooner had you known?

6/1 Dinosaurs and antigravity:
http://www.bearfabrique.org/sauropods/biganims.html
\_ it was once "proven" that you would suffocate if you moved
faster than 20 miles per hour. What a load of crap.
\_ /.
\_ It's \. not /. -- bill gates
\_ Yeah, but read it. It proves that at one time the earth's
gravitational pull was much lower.
\_ No it doesn't. Read the responses in /. and you'll see
refutation of the numbers.
\_ Not surprisingly, slashdotters are wrong. Bad math.
\_ I can't find anything on http://slashdot.org searching for
dinasour. However it seems highly unlikely that they
would screw up the trivial math. It is not the math
that is problematic but the underlying assumptions.
\_ maybe that's because its spelled DINOSAUR!
\_ Maybe the atmosphere was richer in oxygen such that muscles
could grow much stronger and withstand a much higher force-
per-unit-area than those in modern animals. Maybe the winds
blew much stronger than nowadays such that a glider could
take off easily. Just some idea. -- yuen
\_ Wind might help the flyers but doesn't help a 70+ ton
beast stand up. I don't know enough anatomy/biology to
say anything about your oxygen theory. Where's a bio-
dynamics major when you need one?

6/1 Prove that gaussian is the only function family closed under
convolution. ie, forall f,g in H, exists d in H st d=conv(f,g) ===> H
is gaussian family.
\_ The difficulty of the problem hinges on the definition of
'function family.' I could, for instance, come up with many
'function families' of one element each for which the above would
hold.
\_ The difficulty does not hinge on the definition of the
function family in the trivial way you suggest; it is deeper.
There exist uncountable sets of functions H
such that for all f,g in H, f * g is always in H. One
example of such a family is the set of sinc functions
A sinc (w x) with w in [1 2] and A being any real number.
This was what I was trying to point out below. -emin
\_ Right. The definition could be made too narrow (to make
closure easy), or too wide (for instance by making H the
set of all continuous functions on R), which would also
make closure easy. The point, in both cases, is that
we are missing the definition of what a function family is.
My guess is that a function family is a set of functions
with the same finitely expressible closed form (finitely
expressible to avoid the fact that continuous functions on
R all have Taylor expansions).
\_ Utter nonsense about complete set of real functions deleted.
Take a math course, for crying outloud. -- motd math censor.
\_ fuck you.
\_ This isn't true. Let f(x) = g(x) = sinc(x), then f * g = f.
Also, if you let f and g be generalized functions
then f(x) = delta(x) = g(x) results in f * g = f = g.
I belive what you are thinking of is that if you restrict
f and g to be probability density functions then Gaussians
are the only pdfs closed under convolution. Not sure how
to prove this off the top of my head. Please let me know,
when you find out. -emin
\_ Depending on the minutia of the formal definition of PDF,
a delta function may be considered a PDF as well (since
the integral is defined to be 1....). Then, of course,
delta can also be considered a Gaussian with 0 st dev.
\_ yeah, sorry i meant pdf. i'm aware of the delta function case,
but i guess i'd like to define "in the set of" as
"approaches an element in the set H, in some sense". also,
i think the proof i have in mind requires L2, which deltas
aren't. so my proof was going to look something like:
since it's a PDF, it must be the square of some other function.
look at the fourier transform of the square of something, and
realize that it must be closed under multiplication in the
fourier domain. assuming that the function is in L2, that
constrains it to a large class of functions, which includes
boxes and exponential functions. then i was going to use
the fact that this is the fourier of a SQUARE of a something
to show that within the exponential function, it must be
gaussian. i don't know yet how to get rid of the other families
that are closed under multiplication. -ali
\_ man, do you always have a comment on everything, mr. fricking
i know everything about anything?
-- alum who dislikes you intensely
\_ Disliking ability in others is the only form of evil
I know. -- Ayn Rand #1 fan
\_ having ability is one thing, discussing
topics like this here is another...go to some
math newsgroup, don't clog the motd with this
extraneous garbage.
\_ Oh bull-fucking-shit. Any kind of math discussion is
vastly better than most motd discussions, and you know
it. It's no crime to be stupid, but it's a shame to
be bitter too.
\_ The motd has helped me out a lot. Consequently I feel
a responsibility to give back and try to help answer
questions which I have a clue about. I'm not trying to
show off. If you have a suggestion how I can try and
contribute to the motd without offending you, please
let me know. -emin
\_ i don't think "alum" was referring to you. you typically
provide the kind of insight the rest of the CSUA is
completely incapable of providing. -ali.
\_ i'm talking about ali, not you emin.
\_ you stupid shithead. i'm the one who asked the
initial question. if you have a problem, feel
free to post your own moronic "how do i make
text bold using html" questions. -ali
\_ 'Take your math elsewhere' stupidity deleted, due to
its inherent idiocy. -- motd math censor.

4/32 Stat 200a vs Stat 101 vs Stat 134 -- any comments? Experience with
any would be appreciated too. (Assuming that purpose is applications
in an arbitrary area of theoretical CS)
\-sigh, i guess i will wade in: if you let me know what topics you
\_ Can you describe the subject matter please? I am too lazy to
look it up.
are interested in terms of math-speak [theortical CS to me is more
algebra than probability] i might be able to make a recommendation.
are you interested in models, time series, probability/measure,
game theory or more specific stuff like genetic algorithms, neural
nets, baysian stuff/AI? --psb
\_ bayesian. -- card-carrying bayesian
\_ And in general, I hate genetic algorithms. Why are they even in
\_ This is why I should have signed my blurbs in motd.
-- alice
the same category as neural nets and bayesian nets? They are
completely unprincipled. There are no convergence results for
genetic algorithms. In fact, you are not even guaranteed to
improve in each iteration. The whole thing is a scruffy atavism
be an engineer, i.e., look into EE126 and EE226.
from the free-swinging days of AI when any yahoo could get a PhD
by writing an Eliza program. -- card-carrying bayesian
\_ 134 was kinda fun in a gambler's anonymous kinda way.
\_ Real men (and real CS theoreticians) take Stat 205ab. Given
\_ and don't forget those strange women that know how
to do math. You know, women that are men.
\_ "MATH IS HARD! LET'S GO SHOPPING!" -Barbie
\_ Actually that was 'Malibu Stacy'
\_ Real men don't get their panties in a twist over
convenient abbreviations like the phrase "real men".
\_ Morons. This is why I should have signed my blurbs
in motd. -- alice
\_ Signing it didn't make a difference. Go fuck off.
\_ Previous animosity not registered.
your choices, however, I'd go with Stat 134, because they seem
to talk about more complicated stuff like random processes. It
really depends on how you plan to use it. If you just want to
know enough to get by in CS 174, then math 55 or CS 70 is more
than enough. If you are serious about stat, but your math
background is not very good, then do the next best thing and
be an engineer, i.e., look into EE126 and EE226. --alice
\_ Given decent math background (core upperdivs), and completion
of cs174 (fwiw). Explain difference between 200 and
205 series; it seemed like 200's are more hardcore
than 101/134, and 205 seems less comprehensive from
catalog description.
\_ 200ab are for business/economy majors, is my understanding.
\_ One of the things I noticed is that EE226 and several
IEOR classes require the 200's. Biz/econ majors?
\_ Ignore the requirements. YOu can pick up whatever
200 stat you need while taking those classes.
Like I said, real men take 205ab, but not with Klass next
semester--I heard he's a terrible teacher--take it with
Pitman the year after. You'll run through measure theory
in the first hour of the first lecture. (You'll return
to it, don't worry.) Then you go on to the good stuff
like the Laws and the Processes. It'll be very mathematical,
but well worth the effort. This is all hearsay, btw, I
haven't yet taken 205. To the best of my knowledge, you
don't need such a solid foundation in stat for any CS
theory courses. However, you'll probably have a much more
transcendental experience in Sinclair's MCMC class
with some 205 under your belt. Mmmm, the Sinclair Eclair.
-- alice
\_ For fun with AI, take Michael Jordan's year long series
of courses on graphical models. They are cross-listed
as graduate stat and graduate CS. Very cool stuff.
-- ilyas
\_ I thought he was a retired basketball star and
ex-talk show host?
\_ No, he is actually a star AI researcher,
freshly stolen from MIT. He works on
variational approximation methods that allow
one to deal with very large graphical models.
-- ilyas
\_ Oh yeah. Forgot about Mike's classes.
They will be excellent. Knowing him, he's
probably going to go through calculus of
variations, variational methods, mean-
field theory, and general statistical
mechanics in one lecture. It'll be a blast.
-- alice
\_ My ass still hurts from last time.
-- ilyas
\_ Please don't make me picture your
ass, ilyas.

4/11 emarkp, ilyas, ali, are you guys in grad skool?
\_ tell us about the stars ilyas!
\_ I am not in grad school because I lack the grades and references
to make it to a first tier school. Thus, I am trying to get my
foot in the door by doing something reasonably impressive in the
industry. -- ilyas
\_ the stars! - Irami Osei Frimmpong
\_ grad schools don't look so favorably upon most
industry experience. They want to see letters from
people they know in industrial research or academic
research (or so says Aiken...) Besides, ilya, I
always figured you more as the capitalist worker
exploitation type... hmm... ;-) -brg
\_ Industrial research is, unless you work at IBM, an
oxymoron.
\_ that's bullshit: at&t bell labs, hp labs, microsoft,
and of course the many biotech firms that have
been founded by research scientists with the intent
of doing research in a specific direction. i won't
even mention all the major chemical companies with huge
research divisions, such as Dow.
\_ Okay, Microsoft research is an oxymoron.
\_ no, it's not. they have hiret some badass
quantum computing theorists. if you .ook
at the paters in phys rev a on quantum
information, alot of them come from microsoft
peopl.
\_ Quantum computing research is an oxymoron.
And learn some damn grammar/spelling.
\_ Microsoft employs some of the world's best
AI researchers like David Heckerman, and
Christopher Bishop. -- ilyas
\_ Is that why those dancing paper clips
seem so intellegent?
\_ Aiken is right.
\_ In that case I lose. -- ilyas
\_ the industry is full of $$$!!! why the #*( would you go
back 2 skool???
\_ define first tier and second tier (first tier == top 5?
second tier == the next 10 after that?)
\_ first tier == { "Berkeley", "Stanford", "Carnegie Mellon",
"MIT" }; // No particular order
second tier == { "Cornell", // VERY close to first tier
"Brown", "Princeton", ... (there's quite
a few and even if I tried to list them all,
I'd miss one) };
-dans
\_ i'd say you should put Georgia Tech in there if you're
going to put CMU. the top 3, everyone says is Stanford,
Berkeley MIT.
\_ Georgia Tech doesn't come close to CMU or even Cornell.
And in reality, Stanford is considered top tier even
though schools like Georgia Tech, Utah, and UNC have
arguably better programs...
\_ It must be listed in alphabetical order! Berkeley, CMU,
MIT, Stanfraud. -- yuen
\_ What about CalTech?
\_ why are you asking these people specifically? and you should
sign your name if you want these people to respond.
\_ I don't know why you're asking about me specifically. But no, I'm in
industry with a BA in CS. -emarkp
\_ well, you sound like a nweaver-wannabe and he's a grad stn
\_ What does that even mean? Do you mean that not using ad
hominem attacks makes me look like a grad student? Small world
you live in isn't it? (And sign your name.) -emarkp

3/28 I nuke that whole fibonacci discussion. I think it was definitely
created to torture students throughout junior high, high school,
and college. And that guy who called me stupid...kiss my ass bitch!
Shit...if it was so *easy* and so *simple* why was there a big
ass post here on the motd?? Fuck fibonacci, go talk about the
Fourier Series, Laplace transforms, Legendre polynomials, etc, etc,
just no more fib...it grows tiresome. Or talk about Reality brand
female condoms...better or worse than the norm? blah blah blah...
\_ i think you nuked it because people were exposing your stupidity
too much.

3/27 What's the running time (big-O) of fibonacci series? I can't find it
on CLR. It only talks about the golden ratio shit.
\_ F_n=(p^n-(1-p)^n)/sqrt(5), p=the golden ratio. --Galen
\_ CLR was the most worthless piece of shit book I have spent my
money on. It's worth more as fire wood or a shooting target than
an academic textbood.
as an academic textbook.
\_ Go read some Sesame Street literature, then. There's a good
REASON that CLR is the single most popular intro algorithms
text in the world.
\_ O(1).
\_ dumbass
\_ A numeric sequence can't have a running time, only an algorithm
can. Please restate your question. Also, Fibonacci numbers are a
sequence, not a series.
\_ How about "What's the running time of evaluating the n+1-th
number in the Fibonacci sequence F(n) by using the recursive
algorith F(n)=F(n-1)+F(n-2), F(1)=F(0)=1?"
\_ The naive implementation is exponential, the slightly less
naive memoizing implementation is linear.
\_ The cool implementation is constant time. You can derive
a formula like F(n) = a * b^n + c * d^n. I don't remember
the coefficients, but you can look them up or derive them.
If you need the formula and you can't find it, email me
and I'll take the time to derive the constants. -emin
\_ F_n=(p^n+(1-p)^n)/sqrt(5), p=the golden ratio. --Galen
\_ uh, if you have to use "to the power of n", for arbitrary
n, i don't think it's constant time...nice try though.
\_ "To the power of" is O(1). Nice try though.
\_ I'm impressed...with your stupidity. I mean,
you can't really be THAT clueless can you? You'd
have to be TRYING to be stupid to come off that well.
I really hope you were expressing something in an
odd and painfully obtuse way rather than blithering
utter and complete nonsense.
\_ Go read a book, moron. Let's see you do O(1)
ANYTHING. O(1) means you don't even have time
to read the entire input. Exponentiation in
arbitrary precision is O(log) with respect to the
exponent. Actually something like O(n^3) w.r.t.
actual input size, since the base has to be
multiplied by itself O(log(exponent)) times.
\_ BTW, what's the Fibonacci series famous for? It might be useful
for teaching computer science, but for math itself what's it
useful for?
\_ It comes up in the wierdest places. People have used the
fibonacci sequence to analyze the stock market (successfully).
\_ yep. there is a journal called the "fiboonacci quarterly"
devoted entierely to such weird cases. it should be in
the math library if you're interested.
\_ If the stock market was that easily analysed, we'd all be
billionaires.
\_ you mean you're *not* a billionaire?
\_ I meant the rest of you peasants.
\_ Modeling the reproduction rate of rabbits.
\_ yeah, i hear you on that one. the most i've ever seen it
for is the continuous torture of students throught junior high,
high school, and college. if anybody can actually point out
a url which proves that this thing actually has a practical
application in reality, i'd be really pleased to see it...
die, fibonacci, die!!!
\_ Torture? Fib series is trivial. Where'd you go to school?
Dummy High?
\_ C is for Coo^WYour Grade and it's good enough for you!
\_ If that's the most you've ever seen it used for, you must
be an inexperienced college kid with little view of the
wider world beyond the school walls. That puts you in the
right place.
\_ for modeling the rate of spawning of new rabits in the wild -ali
\_ This is important because....?
\_ because it also models the rate at which i and my progeny
have been doing your mom for the past two years. -ali
\_ Try Fibonacci heaps.
\_ Whatever. The complexity of the heap operations incur so
much overhead that they eventually end up costing a lot
more to implement than with an alternative and simpler
implementation thus cancelling out any improvements gained
from lower running times. This is as useless as Straussman's
(sorry if I spelled his name wrong Ilyas). Big deal. We can
matrix multiply in O(n^2.7) time instead of O(n^3). It turns
out to run slower on most machines anyways so why bother.
\_ what the fuck are you talking about? name another data
structure that implements priority queues with logn insert
and 1 retrive. the "simpler" alternative you have in mind,
is it an insertion sort or something stupid?
\_ Maybe he is talking about standard heaps which have logn
insert.
\_ Strassen's is getting to be O(n^2.3) now. And even the
O(n^2.7) implementation becomes faster than normal
multiplication for sufficiently large arrays on the machines
where 170 homework is done, at least. -- ilyas
\_ The best known, n^2.376, isn't based on Strassen-Winograd
original... not that it matters, of course...
\_ Do you have any idea how big the matrices for interesting
real-world problems tend to be? Do you have any idea
how much less (n^2.7) is than (n^3)? -blojo
\_ Why, do YOU? Because it isn't all that large. Even a lame
implementation passes the threshold at about 150x150
matrices. A _lot_ of problems involve much larger matrices
which are sufficiently dense for sparse methods not to
work.
\_ Are you arguing for or against Strassen's?
\_ That's not how it is in my industry (games).
Nobody doing a complex system will write brute-force
matrix math and expect it to run okay. It's all
about multigrid methods, frequency-space operations,
you name it. -blojo
\_ while (player_still_alive()) {draw_dot(x,y);}
\_ Ideas similiar to Strassen's algorithm are used for
fast FIR filtering which is widely used in all sorts
of DSP algorithms. I don't know if people thought of
fast FIR filtering first or Strassen's algoirthm first.
However, the point is that the ideas behind Strassen's
algorithm turn out to be very useful. IMHO the reason
to study algorithms (even weird stuff like Strassen's
algorithm and Fibonacci heaps) is so that when you
have a particular practical problem you can come up
with clever ideas. -emin
\_ Strassen was there first.
\_ I'm sorry, Strassen's should *never* be faster on modern
architectures, where multiplies are as fast as adds. Strassen's
trades off more adds for fewer multiplies. As long as you've
blocked your implementation for cache and registers, and copied
when you have low-associativity caches or TLB, then you're OK
without Strassen's. -nick
\_ Uh, go read the book again. Strassen optimizes away MATRIX
multiplies, NOT scalar multiplies. If we knew how to multiply
matrices as fast as we can add them (O(n^2)), all of Strassen's
instead of 8 muls, you have 7 muls. -ali
stuff would be obsolete, yes.... But we _don't_
\_ Isn't this one of the advantages of a Quantum
Computer over standard computers.
\_ Oh, shut the fuck up, and consult the literature.
\_ Find a new book. At the instruction level, a multiply is
a multiply. Thank you for playing.
\_ Wow. Are you just a total idiot or what? For a square
matrix of size n x n, addition or scalar multiplication
requires O(n^2) operations, whereas naive matrix
multiplication requires O(n^3) opations. Yes, add and
mul are single instructions, but Strassen attempts to
reduce the number of those instructions.
\_ This was exactly my point. So there's no reason,
as you said, why we should use add instead of mult.
\_ because while add and mult are equally fast,
add is faster than mult. Duh! --pld
\_ look, strassen's replaces a multiply by 14 adds so that
instead of 8 matrix muls, you have 7 matrix muls. -ali
\_ Thank you for reaffirming my point that an mult is
the same difficulty computationally as an add, so
there's no need for all these Strassen methods and
their variants.
\_ it replaces 1 matrix multiply by 14 matrix adds.
A matrix mutliply (brute force) is O(n^3). A
matrix add is O(n^2). are you really this dense?
\_ But they're the same if n is 1, so fuck you!
\_ I think you can use a generating function z() to compute the nth
fib. number in constant time- hence the O(1).
\_ Formatting fixed.
\_ The above function IS the generating function and it's NOT
O(1) with respect to input size. Read above posts.
\_ Think outside the box. The answer is there if only you
would reach for it.
\_ i think bigdickbastardpedant's complaint is that you can't
generally compute e^x in constant time, because you need to
compute at least a taylor series or something, and the number
of terms used does depend on x, as larger x's are more poorly
approximated with few terms. i don't know of a way to compute
e^x in time independent of x either. -ali
\_ "Hello, Pedant." *clickety click*
\_ Well The Pedant needs to go re-read exactly what O() notation
is all about and how to properly compute it. The size of the
input is unrelated to the O(), therefore The Pedant is not
only a pedantic idiot, but is simply flat out wrong as well.
\_ you must have this strange verison of O() notation that
depends on the phase of the moon or something.
\_ If sorting is O(n log n), what does n measure? lumen? -pld
\_ fibonacci sucks big dick
\_ I wish. but mine wont fit
\_ You wish a guy suck your dick?
\_ You wish your writing good grammar?
\_ Why not? Who cares who does it? Lips & tounge are
lips & tounge.
\_ Sigh.
\_ Ahhh.
\_ Is formatting so hard? I think I'll start purging all
content-free comments that are poorly formatted.
--formatting nazi
\_ Do it. Blow 'em away!
\_ what the fuck is a tounge?
\_ An extremely clever anagram.

3/6 Computer science theory shmatheory. I'm not a phd candidate like
nweaver or dpetrou but I'm making #)(*$)# more $$$ than they are.
\_ You know what they say about fools and their money... -brg
\_ nweaver probably still has far more $$$ than you (gotta love
rich parents) and dpetrou is definitely far more intelligent
and happier with his life than you are. All you have is money,
and that is fleeting.
\_ Nice to know nwaever can afford to mooch off his parents
and join the intelligencia and look down upon us poor slobs
who have to *work* for our money. You have no basis of
comparison between dpetrou and the anonymous person above,
so nothing further need be said on that. -not the above
\- well. love is still better in the end than $$.
( future IPO millionaire)
\_ money can't buy happiness, but it can buy... legos! yesh!
-current IPO millionaire
\_ Money can't buy love but it can buy the alleviation of most
forms of personal suffering. After your basics are met and
are guaranteed to remain so for life, any misery remaining
is your own fault. Go see a therapist.
\_ Money can't buy yer mom, because she is free.

3/1 Today we'll be talking about artificial intelligence by useing
examples from The Matrix with the help of Stuart Russell. 308 LeConte,
5pm. all are welcome to attend! -sofia
\_ Someone go there and protest that Matrix demonstrates
nothing about AI. Watch 2001 instead.
\_ One more reason to STAY OUT OF INDUSTRY, COME BACK TO ACADEMIA!!!
\_ One more reason to STAY OUT OF SINDUSTRY, COME BACK TO ACADEMIA!!!
\_ Does academia include free use of a spell checker?

2/29 What's the difference between a context-free-grammar and a
context-sensitive-grammar?
\_ Context-free: a rule maps a non-terminal onto a string of
non-terminals and terminals; decidable by a pushdown automaton
Context-sensitive: a rule maps a string of terminals and
non-terminals to a _longer_ string of terminals and non-terminals;
decidable by a linear-bounded turing machine, but not by a PDA.
Universal: a rule maps a string of terminals and non-terminals
onto any other string of terminals and non-terminals (aka
Universal Rewrite Rules), decidable by a TM, but not always by
a LBTM/PDA. For more, RTFM; the motd is not a math book. -alexf
\_ I wonder who is asking 172 questions on the motd? -brg
\_ A lazy idiot. -- ilyas
\_ Yes, and anyone dumb enough to take 172 is just an idiot.
\_ Hey, for the record, 172 was my favourite class at Cal.
But asking such ... class-related questions on the motd
seems pretty lame to me. The least you could do is
troll well. -- ilyas
\_ And mie favourite klass was Collej Righting 1A
becouse we lerned to spel words like favourite.
\_ Anyone who doesn't like the same classes as ilyas is a
troll.
\_ Anyone who says stupid shit like:
'\_ Yes, and anyone dumb enough to take 172 is just an idiot.'
is a troll. -- ilyas
\_ ilyas hath spoken and so shall it be!
\_ I liked 172 a lot, even though I got my ass kicked and
I am definetely not into math... -muchandr
\_ more like 164 I bet.
\_ 164 almost never covers CSLs/CSGs
\) why did everyone bitch about my 164 class then? -aspo
\_ Who cares?
\_ 164 is boring. 264 is more interesting.

2/28 If the push-down automton can accept the language consisting of all
words in the form (a^n b^n, n=1,2,3,...), how come no pushdown
automaton, deterministic or non-deterministic can accept
(a^n b^n c^n, n=1,2,3,...)? How would a linear bounded automaton
accept this language?
\_ Just write a perl script for some computer. Make k large enough
\_ Do you own homework.
to make 3*n*k be equal to the RAM size of the computer.
\_ 'your'
\_ 'typo'
\_ 'idiot'
\_ Think of this the next time you typo, idiot.
"That's how."
\_ and people wonder why the csua is a sysadmin farm
\_ pumping lemma pumping lemma pumping lemma, hehe.
\_ Do your own homework.
\_ Are you saying no one has shown that it can, or are you saying
someone has formally proved that it can't?
\_ "Someone" has formally proved that it can't, and YOU CAN, TOO!
With just a small 4-unit investment into an intro complexity
class, YOU TOO can go around saying cool words like "pumping
lemma", "LBTM", "Savitch", and "EXPfuckingSPACE." Take 172,
and CHANGE YOUR LIFE FOR THE BETTER! -alexf (real answer: pump)
\_ I did take 172 in Spring '91. I just had a lousy professor
(Anvari).
\_ How relevant is complexity, architecture, automata&languates,
logic&systems design, theory of computation? NONE. I took a
c++/Java class and now I'm making 80K/year. -not CS major
\_ relevant to what? just because most people in computers
dont need to understand fundamentals doesn't make it important.
this is like all those idiots who think that because they make
tons of money in software hardeware is useless. without
people to concieve of new kinds of computing devices who understa
nd theory and people to build those devices, you would not
have anything to work on for your 80k/yr. no one is going
to pay you 80k/yr to write addition algorithms on Babbage's
difference engine. not relevant to *your*life != not relevant.
\_ I happily make tons of money in a non-hardware field and
fully appreciate all the hardware toys that come my way.
Not a CS major and making more than the clown above who
doesn't get it. Every advance in either software or hardware
is good for everyone's bottomline.
\_ Is your code maintainable and extensible? Probably not...
\_ Are you in school and making +80K? Probably not.
Are you in industry and making +80K? Probably.
\_ Industry is for brainless people and academia is for
brainy people. Industry sucks and academia rules.
B1FF G0 BAC|< 2 SK00L!!!!!!!
\_ "I work for academia and get paid less to do less,
therefore I am morally superior and more intelligent
than my industry counterpart." This is such a total
crock. It was hard to get a good first industry job
coming from academia because in industry they know
the book worms don't know how to produce, can't work
and can't get along well with others. Academia isnt
even academia anymore. How many rooms and buildings
are named after companies or CEO-ish sponsors? How
many projects on compas are paid for in whole or in
part by industry? You think that's free money from
the goodness of USA INC's heart? Academia is the
cheap research arm of industry, today. Traditional
academics are dead. Long dead.
\_ Idiot. It's the long term research in the
industry that is dead. Go away, you superficial
software drone.

2/25 Next week's topic in the science fiction DeCal is Artificial
Intelligence. We'll be watching The Matrix on Monday @6pm 160 Dwinelle,
and Stuart Russell will lead discussion on Wednessday @5pm 308 LeConte.
All are welcome to attend either class. -sofia

2/16 I always ask this simple computer science question: What is the
running time of an insertion sort? 50% of the time, the candidates
can't even answer that question correctly, yet they are making
50-60K/year. What is wrong with this industry?
\_ Maybe you're the one with the wrong answer.
\_ Labour shortage. I used to be proud of how much I was making
until I realized a lot of idiots make even more.
\_ What IS the running time of an insertion sort?
\_ O(n^2)
\_ Wrong answer. Right answer: "Under what performance model?" -nick
\_ Average case?
\_ That's just the issue of which asymptote to use,
not which performance model to use. -nick
\_ Enlighten us--what do you mean by "performance model"?
\_ RAM, PRAM, PMH, LOGP, BSP. When is merge sort
likely to be faster than quicksort? It depends
on which model you use. RAM says quicksort, PMH
says merge sort on machines with caches. (independent
of the partially sorted issue).
\_ I guess I'm just an idiot. What do the
acronyms mean?
\_ You're fired. The answer was O(n) because the data was presorted
and inserting one more element in a presorted list isn't O(n^2).
More specifically, the exact correct answer is that not enough
information has been provided to correctly answer the question.
an idiot and is asking the wrong question. I *HATE* having a
\_ You're fired if you can't figure out how to insert into a
sorted list in less than O(n).
right answer and ask it properly. This goes out to all dumb
fucks out there who don't know what they're asking. You're not
penalising people for lack of clue. You're penalising them for
not being able to read your mind! That's why so many job reqs.
\_ You need a 'special' list for that. Lists don't have
random access, and array don't have constant time
simple question across without wrongly and unfairly assuming it
insertion, so you have to marry them.
choosing the wrong interpretation of the many valid possible from
your _very_ _poorly_ designed question. How did you graduate
from Cal and get into a position to interview when you're not
capable of asking an intelligent question in a way that can be
understood by others in the field? Sheesh. I really hate the
arrogant inarticulate geeks who are incapable of seeing any fault
in themself. The fragile ego can't take it.
\_ Did you know that Phillip Nunez invented the skiplist?
\_ By the way, what is the running time of inserting
n elements into a vector? -- ilyas
\_ tjbP?
The person above "ragging" on people getting the wrong answer is
an IDIOT and is asking the wrong "question". I *HATE* having a
totally *STUPID* interviewer like that. If you're going to ask
any sort of technical "questions", you better fucking *know* the
right "answer" and ask it _properly_. This GOES OUT to all dumb
fucks out there who don't know what they're ASKING. You're not
penalising people for lack of CLUE. You're penalising them for
not being able to "read" your MIND! That's why so many job reqs.
specifically say "excellent written and _oral_ communications
skills". That's to avoid _dummy heads_ like you who can't get a
simple "question" across without wrongly and unfairly ASSUMING it
\_ When I grow up, I want to go to Bovine University!
is the other person's fault for _not_ reading your mind and
choosing the wrong INTERPRETATION of the many valid possible from
your _very_ _poorly_ designed question. How did you GRADUATE
from "Cal" and get into a position to INTERVIEW when you're not
_capable_ of asking an intelligent "question" in a way that can
be UNDERSTOOD by others in the field? _Sheesh_. I really hate
the arrogant inarticulate "geeks" who are incapable of seeing any
fault in _themself_. The fragile ego CAN'T take it.
\_ Right on.
\_ Exactly. Besides, known questions can be looked up. Better
questions investigate how a candidate thinks and how he/she can
communicate with you.
\_ The appendix to the "Deep C Secrets" book has a good
summary of answers to some of the most common MS & SV
programmer interview questions.
\_ More importantly, who cares? -sysadmin over 90k
\_ 50-60k? 65k is starting salary nowadays...
\_ shit, i got screwed again
\_ A while ago I interviewed a few people for software
engineering jobs. One of the easy questions I asked was: What
is the running time of quicksort? Four out of five candidates
got the right answer. The fifth had a certificate in computer
science from Microsoft University. He didn't have a clue about
\_ When I grow up, I'm going to Bovine University!
quicksort. Did you notice a corellation between university
degrees and people knowing about insertion sort? -emin
\_ What is your answer?
\_ The answer I was looking for would be O(n log(n)).
Answers like O(n log(n)) in average case and O(n^2)
in the worst case would be even better. A discussion
of computing models would have been fine as well.
Basically I wanted to make sure we hired people who had
a clue about efficiency, not just people who knew the
syntax of a programming language without knowing anything
about efficiency. It was not a trick question. It was
an easy question. -emin
\_ Actually, if that's the answer you're looking for, you
better refine your question. Instead of asking for the
running time, which is subject to interpretation (computing
models, average case vs. worst case, etc.), perhaps you
should ask someone to actually perform an analysis of the
running time for a given algorithm. -dans
\_ I agree. I also asked algorithm analysis questions.
My point I've known people who interview for a
programmer job without any clue of algorithms. You
ask them about quicksort and they stare at you blankly.
\_ I wasnt staring at *you*.

2/3 /tmp/tjb-resume.pdf
\_ Isn't anyone going to do anything?? Scratch one up for the
bad guys...Somebody should anonymously be slipping a transcript
of that tirade of his under the door of the math department.
Why is it the world that assholes like this always win?
-- angry anon
\_ Actually, we should find out how danh got the resume and
see if he was breaking any laws in posting it. It looks
like a scan or fax. Which means he probably had a
physical copy. He also could have had at least the
consideration to destroy the home address and phone
number from the posted file. That alone could be
considered illegal.
\_ When you make a resume and submit it, you're doing so under
the assumption that an entire organization of people and
possibly multiple (contracting firm and the place they send
you) are going to look at it, enter it in mass databases,
etc. You _want_ lots of people to see your resume. It
isn't confidential information.
\_ Thanks for overwriting my comments. Yes you expect people
who may be considering hiring you to read the resume. You
do *not* in general expect to see it posted to a
general-access website. I wouldn't put my home phone,
cell phone and address on a website, but I would put an
email address. I think tjb could take danh to court.
\_ blah blah blah. its the motd. no one intentionally
overwrote your whine. tjb can't prove any harm and
courts are expensive. once you release your resume
you have every expectation that it _will_ become
public info. youre a fool otherwise. tough shit.
\_ Please show me where I stated that the overwriting
was intentional. Or, what, only you can complain
about incompetence?
It's disturbing that you equate illegal with tjb's
abilities to pay for court proceedings. Just
because tjb was a jerk doesn't mean that gives
anyone license to stalk him.
\_ whine whine blah blah whine whine. It's the
motd. things get overwritten. whine blah
blah, bleah. Hardly worth mentioning no
matter how it happened. whine blah whine.
\_ Posting a resume isn't stalking. Name one
law actually broken. If sharing information
about people was illegal, credit bureaus
couldn't exist or make so much money selling
your reports to credit card companies.
\_ But posting the home address/phone number
along with deprecating remarks and
suggestions to harass tjb (all of that here
on the motd) is stalking.
\_ Under what imaginary law?
\_ So tjb can call the cops if he wants.
Good luck with that. No it isn't
stalking. At worst it shows bad taste
on dan's part. If he really feels
like doing something, he should go
get some student conduct board on dan.
Again, good luck. /tmp on a limited
access computer is hardly public,
anyway. Can you say, "Over sensitive",
"Mountain/molehile", or "Wah! Mommy!"?
\_ Look again you moron. The file in
/tmp is a symlink to danh's webpage.
That's most definitely public.
\_ Yeah, dan's soda web pages are
getting millions of hits a day.
Like I said, waah waah waah. Go
bitch to someone who might care,
like your mother.
\_ ep-sample is no more
\_ since when is it illegal to scan in someone's resume?
maybe i want to hire him. I think tjb qualifies
\_ You needed a new asshole?
\_ How can you have GSA appointment when youre an undergrad? by
definition he has to be an *undergraduate* teaching assistant.
Unless the math department is now handing out graduate
appointments to sophmores...
\_ Happens all the time. Occasionally they call them "UGSIs"
but they do everything the same except they don't get
a tuition credit (at Cal)
\_ d00d, m4d B4S1C sK1LLz!!1!!
\_ Is this just me or not? I just looked at it. IMHO, I am much much
more impressed by most of the resumes of various people posted on
<DEAD>soda.csua/~membername<DEAD> tjb's resume looks like an
average nerd type resume, the kind that usually go to grad school
after graduating. I didn't see much accomplishments (aside from
just getting good dull grades) in there. And those grades aren't the
greatest ones I have seen before.
\_ Anyone want to run a check on the 'first person in history
of university' to TA math as an undergrad claim? I'm having
a rather hard time believing that.
\_ maybe he's right about the math 55 claim, since
i bet most serious math students don't bother
taking math 55 unless they are CS majors
\_ my friend TA'd math 16a,b as an undergrad, and had
all the same responsibilities as a normal GSI. it
is quite common. the math department has somewhat of
a labor shortage and honestly does not give a shit about
undergraduate education(yes, i have evidence to back
this up, and no, i'm not saying there aren't some
great individual teachers in the department.) the pay
sucks, the workload is high, and they'll hire anyone who knows
calculus and will put up with the bullshit.
-mathmajor alumnus
\_ it's not supposed to impress you. there are several
strange things, for instance, he made double the $$$ delivering
asian food to the suburbs (??) than he did programming
computers. plus he has MAD BREAKIN' SKILLS. I haven't
seen anyone breakdance since I rented Krush Groove 10 years
ago. I would love to know under what name
he practices his turntablism (for lack of a less stupider
sounding name) skills, DJ TJB just doesn't fill me with
awe. Trevor are you reading this?
-csua member posting anonymously,
just to avoid moronic flames from this asshole
\_ what's so wrong with the type of person who goes to
grad school after graduating?
\_ May be he meant that academic success is not
all that matters in one's life or even on the
resumes.
\_ What's worse? A moron? or the moron who goes thru the
trouble of posting a moron resume and posting to the motd
about it? Okay, so danh is not a moron, but still, makes
ya wonder about these CSUAers -- do they "got life"?
\_ i am a moron today, but I had a lot of fun figuring out
how to make a pdf finally - danh
\_ Making a pdf was fun?
\_ Since it's scanned, wouldn't a jpg or even gif
have been smaller?
\_ In framemaker, it is a simple "save as" routine.
\_ shut the fuck up, cmlee. -tom
\_ obsessing over small details is not a moron trait;
it is a geek trait. Bragging on your resume about your
mad breakin' skills or whatever and listing a food
delivery job as work experience is a moron trait. And
fucking with people who have a presence in every corner
of the industry you someday plan to work in is
DEFINITELY a moron trait. -illuminatus
\_ This is the part I like. All tech resumes pass over
my desk before anyone else sees them. Only the ones
that don't go in my trash can have a chance. This
includes people referred by current employees (as if
anyone would refer this guy). I post the worst ones
outside my office for everyone to laugh at instead of
the typical array of Dilbert comics.
--patiently waiting for tjb's resume to post on door
\_ what company do you work for? it's assholes
like you, not tjb, who make people leave computers
, prefering a pay cut to totally defective pricks
as co-workers.
-scientist making 1/5 your salary who doesnt
work with pricks
\_ I'm an asshole for what exactly? Posting
the funny resumes or throwing out the 100s
of bad ones I get every week? whine blah
bleah whatever. I doubt you make enough
to make 1/5th my salary. But I'll pay
you $5 for each car you properly wash. That
should easily double your salary. But don't
come near me. I don't have time to waste on
ivory tower whiners like you. Just wash the
vehicles and go away.
\_ I agree with the scientist that you
are an anal sphincter, and lacks
basic social courtesy. Not only
are you an asshole, by attacking
tjb, you are also a hypocrite
since you are no better than him.
\_ Still waiting to hear exactly what
my crime(s) are/is. Until then,
you're easily dismissed as the
whiney spewing potty mouthed child
you seem to be.

1/24 Should I expect to put more work in cs170 or m113?
\_ 113 was cake. One of the easier upper div classes I took. 170 had
piles of work but it wasn't hard. It only takes time and lithium to
get through any upper div math class.
\_ lithium? what is this a reference to?
\_ Also a great Nirvana song! Woo hoo!
\_ To the bulk quantities of drugs shipped to the math dept
daily to keep the profs semi-stable. Lithium is for people
with various mental stability problems usually lumped into
the meaningless title of "schizophrenic" (which is totally
different from multiple personality disorder).
\_ Ummm, no. Lithium is used in treating bipolar
disorder, aka manic-depression. It's a mood
stabilizer. Often, anti-psychotics (Haldol as an
example) are used to treat schizophrenia. And the
two disorders are completely different things. I
don't know if I'd call them meaningless, though,
real folks suffer from these things. --bipolar sodan
\_ I'm glad you know a single use for lithium. I would
correct you on the details but wouldn't want to
upset your delicate condition. "Meaningless" in
terms of "a diagnosis of schizophrenia" doesn't
_mean_ anything. Psychiatrists tend to call any
and everything they can't properly diagnose some
form of schizophrenia. Thus the term is meaningless
not the condition itself.
\_ actually schizophrenia is very specific, it just
happens to have many different effects.
\_ "Yeah it's like totally specific, but has like
851+ effects and they like know all about it
which is why anything they can't properly
diagnose is called schizophrenia!! YEAH!"
Uhm, no. You're simply wrong. Think about it.
\_ Don't inbreds have an excess of lithium in their
bloodstreams? -John
\_ I'll have to ask my cousin/brother/uncle.
\_ M113, by far
\_ The CS geeks I know would say 113 because it isn't familiar to them,
the math geeks I know would say 113 because "CS is so watered down
and math is for real" except these same math geeks always talk
about how incredibly easy 113 is compared to their other classes.
Ask ilyas about his mathematical purity of essence and the lack of
similar purity on the part of mere CS losers (in his mind).
\_ I never took either class while at school, but when I started
working, I ended reading most of the CS 170 book because it
had so much useful and interesting stuff. I don't know which
is more work, but if you are in CS you'll probably get more
out of cs170 than math113. By the way, I've always meant
to teach myself abstract algebra, but never quite got around
to it. Can someone point out some incentives for classes like
m113?
\_ Teaches you to hold the same thing in your mind for longer than
the default american attention span of 3 seconds. -- ilyas
\_ Damn ilyas, I never thought YOU'D stoop to such an idiotic
troll. What a bummer. :(
\_ You know I was reading this newspaper article about
new, 'tougher' standardised tests in california. This
article was talking about how some students 'cried in
the middle of the test and gave up' because they thought
the test was too hard. Call the whole thing a troll if you
will but the american public school system really doesn't
teach things like attention span, or proper english, or
foundations of math, or whatever very well. This is even
more surprising because american colleges are in general
excellent and emulated by the rest of the world. -- ilyas
\_ Don't confuse the California pre-college system with the
rest of the country. CA doesn't have a school system. It
has a 12 year baby sitting service. ilyas, you're either
trolling or don't know what you're talking about or both.
The anecdotal "some student in this one article" isn't
proof of anything. I thought you were some sort of self
proclaimed super rational logic genius? Stop trolling.
--American with longer attention span than ilyas
\_ Is the public school system any good in other states?
I would be very interested in any information on this.
And stop trolling yourself, rationality is intractable.
-- ilyas
\_ Take a look at grad theory class prereqs. Quite a few ask
for 113.
\_ Traditional uses for 113--cryptography, quantum physics,
graph theory (networks). Pretty useful stuff, even if
you never do the quantum.
\_ Quantum physics and graph theory my ass. Cryptography,
yes. But never in the class did they mention anything
remotely close to quantum physics or graphs.
\_ Moron. Did your 1st grade arithmetic teacher happen
to go over all uses of arithmetic for, say, quantum
physics? You're not going to deny that it's used,
in quantum physics and elsewhere, right? Just because
most 113 profs don't bring up those subjects, doesn't
mean it's not directly applicable to them. It is.
Ask anyone educated enough in either field.
\_ ok fancy pants. if you know so much, tell
me exactly what part of 113(that isn't covered
in 110) is needed in anyway for quantum mechanics
besides crystalography wich i dont count. ive taken
113 and physics137a/b, and i dont see any connection
. youre lame. you human paraquat.
\_ D00D!!1! U R SO K3WL!!! 2 S3M3S+3RZ OF QUANTUM
M3CH!!1!! K-RAD!11!!!!!
Read a book: Mirman, "Group Theoretical
Foundations of Quantum Mech", ISBN 1560722487
Come back when you're done reading.
\_ I find this offensive. -- non-human paraquat
\_ Math 113 is less useful and is an easy class. So, I'd put more
work into CS 170. --dim (Applied Math)
\_ I think they're about equal. Put more work into whichever you
find interesting. If you're in CS, you'll probably pick up lots
of 170 by osmosis later on, so I'd pay more attention to 113 --pld
\- in my vast experience at the upper div and grad level, math
classes vary greatly in terms of difficulty of grading and
work load by professor ... that difference swamps any
"inherent" differences between various classes. --psb
\_ He's back! --psb #1 Fan
\_ Maybe.
\_ Perhaps.
\_ Yes.
\_ Psb.
\_ Qed.
\_ ED! ED! ED is the STANDARD! Almost-three-letter abbreviation.
\_ ED is not an abbreviation.
\_ EDitor? Hello? Are you dumb?
\_ Huh? I don't get it!!!!

1/21 Just curious, is computer science considered pure science (as in
medical science research) or is it considered engineering (as in
Electrical Engineering)?
\_ Most classes are a mix, though in different quantites. The
ABET classifications give a rough approximation. CS 170 is
one of the last classes in the world to be considred engineering.
Nor is CS 188. While classes like CS 150 and 152 are heavily
engineering oriented.
\_ I guess these days if you concentrate on theory stuff like
the 170 series or AI, it is science. Otherwise it's more like
engineering.
\_ AI = applied math
complexity = applied math
\_ no, math = applied complexity
compilers = applied math
architcture = applied math

1/20 MOTD Poll:
Trevor Buckingham has been made a TA in Math 55 this semester.
IF you have been following the prior developments, then do you
think that:
a. Math Dept should be notified of his prior history by any
individual willing to do so.
b. Math Dept should be notified of his prior history by the
CSUA as the representative body of potentially affected
students
c. Math Dept should not be notified of his prior history.
This is a serious issue; please withhold ballot stuffing, etc.
Results will be considered final at noon on Saturday.
a: 4.5 + i
b: 2
c: 2.5 - i
\_ with a minimum of swearing and ranting, who is this guy?
-alum
\_ The CSUA ought not to get involved, and moreover, if TB
can teach he should -- being subservient to the teaching
establishment is hardly a prerequisite for being a good
teacher. It's well known there is a shortage of even
minimally competent TAs. And if he does anything too
grossly out of line, he can be fired; for those who are
unsympathetic, you might say that he now has a contractual
obligation to put his money where his mouth is. -brg
\_ regarding the half votes: anyone "should" be able to do
whatever the heck they want, whether it's reporting TB or not,
but a notice from the CSUA smacks of ASUC Senate opinions,
and you really don't want anything to do with that do you?
\_ The CSUA has no business getting involved and can only get
in trouble doing so. Just print out paolo's web page
& last semesters posts and slip them under the prof's
door.
\_ How about letting him demonstrate whether or not
he can teach?
\_ This strikes me as a cowardly way to do things. --pld
\_ Wow. I just read that file. Someday, I hope to have the
opportunity to reject him as a job applicant. I wonder if he
realizes how many people on soda are in such positions in
industry?
\_ Go to work in academia (okay, I'm channeling
kchang here) and deny soda motd hosers like this
guy the chance to reject you as a job applicant.
\_ He got an A+ in Kahan's class. That counts for a lot.
\_ He just seems to be immature. I don't think that necessarily
makes him a bad TA. - mikeym
\_ This is a good opportunity for some smartass kid to give him a
taste of his own medicine.
\_ That would be great, except that given his stunning ability
to consider other people's points of view, I don't think
he'll recognize his own medicine.

11/16 do people here have opinions on or interest in quantum computing?
I am a physicist working on quantum computing, and i'm wondering
how many cs people are playing with the idea. at this point,
the practical stuff is all still physics, since no one has gotten more
than a couple qubits to work, but surely there are more neat algorithms
that could be found by cs people in adition to the factoring algorithm(
shors algorithm) and the search algorithm(grovers algorithm.) you
could argue that this is a waste of time, because we don't know if
large scale quantum computation can be achieved, and to that I have
no defense(except that we're working on it, and we have a good chance.)
i'm just wondering.

9.25 Searle will be giving a lecture on the non-computability of the
brain tuesday next week.
\_ What time? What room? -allenp
\_ I'd rather eat bricks. He's an idiot.
\_ Just admit that your crushed because he can prove that you
cant use that crap you learned in 188 to complete the
girlfriend AI project you've been fantasizing about.
\_ Possibly. At least I know the difference between
"your" and "you're". Anyway, I never took 188 and I
got the warez for virtual valerie, so I'm all set in the
compu-porn dept. Thanks for the thought, though.
\_ besides, how many of the sorority girls on
campus could pass a Turing test?
\_ When I was in school, I had this one roommate in
the dorms with the super bimbo sorority gf. I'm
pretty sure she couldn't have. They were friends
with another sorority chick and dude and I don't
think she'd pass either. Nice tits though.

9.7 For those people who are into AI
(or not into it as the case may be):
Searle's 9.7.99 lecture for the philosophy of mind class is on:
The Chinese Room Argument, and various replies to such.
lecture is 9:30 - 11:00, and 9.7.99 is a thursday @ 2060 VLSB.
\_ Meet at 24th and Mission BART. Wear black.
\_ I've noticed Searle replies to very insightful questions
that could be quite damaging to his theories, by dodging
the question and answering just a small portion of the question.
If you don't believe me, go yourself, listen very carefully
and you will see, he does not quite respond to any question
that points to some disagreement with his own theories.
\_ You have to remember that the Chinese Room argument
is against a very specific claim for AI -- not against
AI in general. Perhaps that is why you think he is
dodging the questions? Then again, Searle's sort of a doofas
in general and does that sort of thing...
\_ I took his philosophy of mind class a few years ago and suffered
through a whole semester of his arrogance and dodging. He's an
idiot.
\_ Searle's Chinese Room Argument [sic] is an intuition pump. He
shows you this system and asks: "What is there that can understand
Chinese?" The guy doesn't understand, the paper doesn't understand,
the room and the pen don't understand. However, this is just making
a claim about individual parts, not the entire system. Certainly
no one will claim that individual neurons understand Chinese, yet
a system of neurons will. At any rate, what does Searle and
the philosophy of mind have to do with AI? -- ilyas
\_ Searle's class covered AI among other things when I took it.
\_ I don't think one can cover AI in a week or two. :) -- ilyas
\_ Ilyas you're an ass. There isn't a class on campus that can
cover an entire subject in one semester you supercilious ass.
\_ well, this wasn't meant to be a post for a debate, altho I'm
glad some people are talking about things other than ed and
unix. It was just an informational post for all our new members
who get the motd upon login. Thanks for your opinions tho.
\_ JOVE!!!!!
\_ _Pico_, buddy. http://www.newgrounds.com/pico
\_ EX!
\_ /bin/cat > filename!!!

8/11 On the off chance that anyone is familiar with such things
I'm having a hard time trying to understand the implementation of
the algorithm for division of large numbers presented in Knuth.
This is largely due to an ambiguity of the order of "Set; test for
this and that; if true, do something else; repeat test if a third
thing is true." (Repeat once or many, and which steps?)
Section 4.3.1, Algorithm/Step D3, if you can help. Thanks. -calbear
\_ Dude, you are one boring man.
\_ What's the matter, INDUSTRY MAN? Don't have the brain to
understand Academia Man?
\_ FYI, it is industry and it's not because it's my area.
(If it were, would I need to ask?) -calbear
\_ Walk on over to Don's office and ask him. Tell him I sent you.
He'll know what to do. -ali.
\_ No one's ever there, but when there is, I'm sure your reputation
will precede you, Ali. Anyway, I wrote him about the ambiguity.
-calbear

8/6 So, i'm just wondering, how important is Math 53 (multivariable
calculus - i believe it was 50a in the olden days) to a non-graphics
software engineer career.
\_ Math is useless. Major in the social sciences. Go to law
school. Learn some social skills. You'll make more money and
meet better looking people.
\_ All math is massively valuable to intelligent people who intend
to have careers using thier brain in any respect whatsever.
\_ In fact I am of the opinion that an entire second major (in math)
is worth the time and effort if you have enough units to spare.
-- ilyas
\_ keep in mind there are all kinds of math, so if you are not
into "the calculus" or maybe don't believe in real numbers,
there is still all kinds of logic, algebra, and formal calculus
that can be useful in later life. friendly intros in the philo,
comp sci, cog sci, and linguistics dep'ts exist so you don't
have to suffer a grad level math class you didn't mean to try.
\_ Spelling looks fine to me. Some of the grammar is spotty.
If you doubt the usefulness of a math class, you should probably
switch to business, or some other major thot does not require
brain usage.
\_ Why bother getting a CS degree. Just get a job.
\_ It was Math 50B. Math 50A was linear algebra and o.d.e . It may
or may not be useful depending on what sort of software you
develop. Take it anyway. --dim
\_ Math 50A became Math 54, Math 50B became Math 53 (I was taking
them during the rename). I don't do graphics and don't find
the material to be particularly relevant to anything I've done
since then, but I feel that math classes like that are good
for improving general problem-solving skills (which are very
relevant to what we all do as computer programmers). They're
also an annoying form of torture, because Berkeley doesn't
seem to have any profs left who can teach undergrad math. You
either get a good TA and learn from them, or you suffer.
\_ You don't need it, even if you do graphics -muchandr
\_ U must n0t B smairt bc eye red 0n D m0te-D dat 2 B smairte eye
nede 2 n0e l0tz uv maths s0 eye kan werk for 3d-ef-x or da
d00m guyz n B k00l! 0nlee maths peeple R smairte!!!1111@@@
\_ I dispute this... if you are doing graphics at anything above
the undergrad level, multivariable calculus is a necessity,
as are a few other branches of math. But I guess that's not
important since the dude doesn't wanna to graphics. Lemme
important since the dude doesn't wanna do graphics. Lemme
ask this: does he plan on doing any kind of specific programming,
or does he want to be an unspecialized (unskilled?) coder?
That will make the question easier to answer. -blojo
\_ It can be useful if you ever have to deal with statistics and/or
probability beyond the basic level
\_ For what it's worth, I remember 50a as being Linear Algebra, not
the same thing as multivariable calculus. There is overlap, but.

3/29 Algorithm question: Is an easy way to figure out the number of
days between two given dates? Eg. given 98/11/05 and 98/12/09
as input, the output would be 34 days? Is there a C function
that can xlate the date into some absolute number and then do the
arithmetic and then covert it back? Thanks!
\_ Let me guess. You're trying to implement If-Modified-Since for
ee 122 right? What I've used since my early days of programming
is time_t time(time_t *t); or 'man 2 time' at the unix prompt.
It'll return the number of seconds since Jan 1, 1970. --jeff
\_ Convert both to Julian dates and subtract.
\_ http://wwwmacho.mcmaster.ca/JAVA/JD.html guess you'll have
to figure out the algorithm from the JavaScript fcns
\_ Or just use mktime(3) and subtract.

3/22 Anyone willing to drive down to Stanfurd on Wednesday? Andrew
Wiles is giving a lecture there at 7:00pm. Me and a friend of
mine would love to tag along :). -- ilyas
\-whos is the target audience of the lecture. where is it at?--psb
\-general audience. Some auditorium (I don't remember, but
the brochure is around the CSUA office). Tickets are $8.50,
I think. -- ilyas.
\_ This is a lecture about... what? Getting your cats and
dogs to get along better?
\_ "Better Breasts and a Tight Tummy in Ten Days --
With Your New Personal Trainer, Andeeeeeeeeeee!!"
\_ Isn't this the guy who proved Fermat's Last Theorem? --PeterM
\_ He's the guy that proved the Tiniyama-Shimura (sp?) conjecture,
which Ken Ribet proved implied FLT.
\- Taniyama-Shimura and it was in the other order
chronologically, but both proofs are quite recent.
does anyone know how to explain what a modular form is
to people with only 50a/50b math? i've explained a structure
of the proof [with a lot of black boxing when it came to stuff
i didnt understand] but i had a lot of trouble trying to
explain the fundamental idea of the mod form. --psb
\_ meow meow meow meow
meow meow meow meow
meow meow meow meow
meow meow meow meow
meow. meow. meow!
-baxter
\_ i have a math degree from berkeley, have published in math,
and dont have a clue what you are talking about(because i'm
into geometry, and have only had 113 algebra.) I think you
just justified the above post about your obscure posts.
\_ Infidel bastard! You have defamed the mighty psb! Your
children will grow up to fellate dead goats for money
and LIKE IT!!
\_Is there much money in fellating dead goats?
I also have a math degree from Berkeley and have
no idea what psb is talking about.
\_ why did I tihnk this was gonna read
"and am looking for a job" after the Berkeley
part?
\_ funny. My brother has a math degree
From trinity College, Cambridge Univ. in
the UK. He designs multi million dollar
financial options and can't balance his
checkbook to save his life. math hmm...
-robin
\_ Use a computer to balance your checkbook.
\_ Use one to fellate dead goats.

12/2 I'd like to take Computer Vision CS280 next year. However, it requires
math 53/54. What's the difference between 53 and 54? Thanks.
\_ 53: Multivariable calculus - integrating over multiple variables
surface integrals, cool looking 3D pictures
54: Linear Algebra but not in the sense that is useful from any
kind of computer graphics work. The only thing you need
\_ yo: graphics != vision. I took 280 with malik
in 1994. grrrreat class!!! -nick
to know for, say 184/284, is transformations/translation
stuff. differential equations are also covered which is not
fun at all. DiffEq is used a lot in EE and E&M (especially
EE120) but chances are you're not going to have to know
what a Wronskian is. I still don't know but those jack
ass math profs (referring to Miller of course) think that
all this is really important.
The basic fact: only about 5% of what you learn in Berkeley
math classes will become applicable to you in the future.
\_ I'd be curious to know whose orifice you pulled this
statistic out of. i use what i learned in berkeley every
day. i have been thankful of having learned at least 90%
of it at one point or another.
you are an idiot if you don't think knowing diff eqs is
important. are you satisfied knowing only how to solve
diffeqs with constant coeffs? that solve 80% of the problems
you will run into as an EE, but that's about it. or are
you just satisifed not knowing how to solve diff eqs at
all? you think you've been doing fine without them, but the
truth is, people in Bangladesh probably think that their
lives are just fine too.
here's what you need from linear algebra for cs280: bases,
transformations, least squares, rank, singularity,
eigenvectors and eigenvalues, orthogonal, orthonormal.
That's basically all of the Anton book. -ali
\_ I never use any math beyond some very basic algebra. I
use *none* of the math I learned at Berkeley. This
pleases me more than you can imagine.
\_ Actually, math beyond basic algebra can be pretty
useful (especially some calc used in physics,
electrical, engineering, and some other science
classes). But the difference between the way a
high school teaches and a college does is that
in high school they teach you how to solve
practical problems whereas in berkeley
they're so caught up in theoretical proofs that
only math majors really care about.
\_ I'm not denying it. I'm just glad I'm not in
a position to need any of it. I'm not even
using HS math. More like Jr. High. Suits me
just fine. YMMV.
\_ well, good for you. but honestly, 90% is frikin insane.
Maybe you had a better prof than I did but I never
had to implement the things I learned from math 54 in
any physics 7 or EE classes to the extent that you
brag about. I admit having to solve simple diff eq's
and integrate relatively simple equations but I never
had to do boundry equations, prove the so called
"Keith Miller's Equivelance Theorem", find eigen vectors,
and do most of that math 54 crap. I'd like to know
whose orfice you're pulling that BS out of.
\_ I dunno, when I took 54 (then called 50B), I
actually used what I learned (when I was awake to
learn) a week or two lagged in Physics 7B...
\_ ali lives on a higher plane.
\_ You are all idiots. I use 0% of what I learned in
Cal. All I do everyday is to count the money I make
and the # of new concubines I get. And I learned how
to do that before I was born. College is useless;
education is stupid. Ignorance is strength and
self-esteem comes from the cavity of an empty head.
\_ Take upper division physics, math, chemistry, or
astronomy (probably others in engineering, too)
and it will make a lot more sense to you. The
lower divison math classes are essential to any
career in science or engineering (hence, they are
required) and really useful in some other fields,
too, like economics. --dim
\_ You can do just fine if you know math just up to Math
53/54. You can do hot sh*t and make much $ with insight
and initiative; you can also do hot sh*t that wouldn't be
possible without sophisticated math knowledge, and make
much $. You may feel fulfilled in either case, depending
on who you are. In either case, you will earn the
admiration of people who you think are brilliant and people
who you think are idiots, and disapproval and disgust from
the same range of persons. -jctwu
\_ Not really. Remember Ted Kazinski, the brilliant
math genius. I don't think anyone liked him.
\_ especially the rabbits. -jctwu
\_ "Math is hard! Let's go shopping!" -Barbie
\_ amen.
\_ Was it Barbie or Malibu Stacy?
\_ One, last I checked...

11/25 CSUA ALUMNI! Come to the CSUA General Meeting on December 2!
There will be a general reunion, and foodP and drinkP afterward.
Come to where the elite meet for NP-complete!
\_ someone should keep extra good minutes for those of us alumni
living too far away to attend - seidl

8/11 Has anyone had any experience with any of the upper div math
classes (in particular 113 and 125A)? What would one recommend to
fullfill the upper div math requirement?
\_ Math 110 (Linear Algebra) is pretty easy. Math 113 is only a little
more difficult, but a lot less useful for a CS type. --dim
\_ Agreed... I was a CS-Math double-major and I use 110 and 113 a
lot more than any of the other upper div math courses. Under no
circumstances should you take 104. 128A is useful if you
expect to do a lot of numeric programming. -mogul
\_ 128A has to be the worst math class ever. sooo boring.
\_I thought 128a was ok last semester with the Icelandic
Prof. Adalsteisson, gave us libs and stuff for C/C++.
Demmel is teaching it in the fall
and I recommend taking it with him. Avoid Rieffel,
boring, and stupid fortran.
\_ I'm not a math person, but my math friends always said 113 was a
piece of cake and 110 was a really hard weeder course. YMMV.
\_ 110 is a more theoretical bend on what was taught to you in
54/50A/whatever. If you didn't do well in lower division,
you'll choke in 110. Of course, for the psychotics who want
to know where integrals come from, there's always 104. It's
a worthwhile course in that it gives you a broader picture of
How Things Work, though I doubt you'll use much of the stuff
in CS. Take it anyway. :-) -- tmonroe
\_ 104 has been relatively easy this summer. Easier than
Math 55 because you don't have to worry about "competition".
\_Well gosh, I actually majored in math, and found them all to be
pretty useful classes. 104 is possibly the hardest class at Cal.
I definitely would not take it just to fulfill a one course req.
I thought 110 was very easy, and 113 was not that hard if you were
willing to stretch your mind in different directions. 128A was
a lot of work, and the math content was kind of low. Probably good
for the CS tie-in. Are those your only choices, or could you take
like mathematical logic, or set theory, either of which would be
much more applicable to CS? Or even 170, which they didn't offer when
I was there. Grrr. --cody
\_ Take 104 if you really want to learn math. Otherwise,
110 or 113, if you just want to fulfill a requirement.
\_ Math 121a and Math 121b were two of the best classes I took
at Cal. I had professor Podles, but some of my friends who
took these classes with professor Neu also enjoyed them very much.
I also took Math 104 which I think is pretty useless. Even though
Math 104 is interesting and you learn some fancy words like
"compact", the only benefit I recieved was learning how to
write a proof (e.g. I leaned what an upside down A and a backword
E mean). Feel free to email me if you would like to read
more of my rant on why Math 121a and Math 121b are FAR superior
to math 104, 110, 113, 185 and most others with the possible
exception of Math 128a/b or the applied math course (I don't
remember the course number for the applied math course).
By the way I got an EE/CS degree with a minor in physics,
but I am working as a software engineer now. -emin
\_ Which 12 step program did you attend?
\_ You used to be able to satisfy the L&S upper div math requirement
with stats 134, which was a basic intro to probability
and statistical methods. not a bad thing if you're not into
most mathematicians' math and you feel a little too focused
towards discrete math and logics in CS --karlcz

6/11 Why the hell is the new RSA command line all screwed up???s
\_ What are you talking about?
\_ RSA has a command line? I thought it was a cryptography
method.
\_ The secret backdoor that the NSA/CIA/FBI/BATF put into the RSA
algorithm means that they can extract anyone's private key
from any encrypted data by running a simple (but highly secret)
Perl script over that data from the command line.

4/9 What algorithms are patentable and what algorithms are not?
(ie. RSA is, quick sort isn't-- wtf?)
\_ uh, are you familliar with the concept of prior use?
\_ none should be --League for Programming Freedom
\_ It all depends on whether you can get a court to agree with you
that an algorithm is (or isn't) patentable.

4/3 How do you solve:
1) summation of 1/n where n = (1 to infinity)
2) summation of 1/n^2 where n = (1 to infinity)
THIS IS A SERIOUS QUESTION, THANKS!!!
\_ If you sum from 1 to infinity
instead, the first one, at least, still diverges to infinity.
\_THANKS! How do you solve by induction w/base case?
\_ Is your homework due at 5 PM?
\_ Already due. Actually I'm at work and I don't have my
calculus book.
\_ I'm trying to solve the interview question: How do you write a
program that can randomly and evenly pick ANY line in a huge text
file, in one parse, where you have very little memory?

3/25 Are there any practical applications of Conway's Game of Life?
\_ xlock
\_ [ignorant babbling about the board game deleted]
\_ A PC moria/angband/rogue/etc clone called ADOM uses it to determine
growth for various plant life in the game.
\_ Just saying "no" would have been shorter.
\_ I thought there was some use for that and other cellular automata
in generating pseudo-random numbers.
\_ there's an encryption scheme based on a 1D cellular automaton
called CA with a standing challenge to crack it
\_ cellular automata are still an inspiration for some artificial
life work. And they're equivalent to Universal Turing Machines,
so you can do math on Life if you want to go to the trouble.

3/20 Would someone please recommend a good book on
Black Scholes Option Pricing Model?
\-who is asking?
\_ John C. Hull's book _Options, Futures, and Other Derivatives_
does a pretty good job - android
\_ duffie's book also does the job, but hull's is better. -fab
\_ Beware that some of the Black Scholes formulas have been
shown to be inaccurate. Look for Robert C. Merton's
\-this is a deep philososphical matter. --psb
books as well. I believe he actually did the math for
Black/Scholes, despite Merton's objections about the
errors in some of Black/Scholes eqns. I think
Merton's book is called "continuous time finance", 92.
\-David Cox [the finance one of from stanford, not the math
guy from i think columbia] has some fine mathematical
finance books. --psb
\-i know i am going to get it for this, but i am having
dinner on sat with a friend of the family who was invited to
merrill-lynch by scholes. if you want me to ask him a specific
question, send me some mail asap. --psb

2/10 size(NT5) = 2 * size(NT4). Oh boy.
\_ Twice the bloat, half the power, quadruple the bugs. Although
I'm pretty sure that size(NT?) will overflow anyway so this isn't
a valid formula on most computational devices. Might be computable
if you had a *lot* of paper.
\_ Isn't quadruple rather optimistic?
\_ I was figuring it'd be quadruple after service pack 4 or 5.

2/8 What does "complied with RSAREF" (or does not use RSAREF) mean?
\_ See "http://www.rsa.com/rsalabs/newfaq/q174.html" It's the "RSA
Reference implementation". There are involved political and
engineering questions surrounding its use or non-use, mostly because
it's kind of slow -- but the algorithm is protected by a patent in
the US, so you might get sued if you try to write your own faster or
more specific RSA code for certain applications without a license
from RSADSI.
\_ If it uses RSA in the US, you need to use code licensed by RSA.
For non-commercial software, that means RSAREF or nothing.
Anything else is illegal. (If you think software patents like
this are stupid, go to http://www.lpf.org and join them.)
\_ Hey, this url doesn't work. No DNS entry, friend. Got a mirror
or something?
\_ Weird. Guess RMS didn't pay the bill. Anyways, try
ftp://prep.ai.mit.edu/pub/lpf/ for now
\_ It's all kinda old. Is this org still active?

1/20 math 110, dubins or frenkel? comments on either appreciated. --jon
\_ dubins is starting to go senile
\_ No math class is worth taking unless it's being taught
by the _man_ himself, H.H. Wu!
\_ They still let Wu teach? How about the French guy, Pew? (sp)

3/31 Someone once told me the story of some graduate math student
who got to class so late that the class was over and there was
some unsolved math theorem on the board. he thought it was home-
work and went home and solved it, and became famous. does anyone
know if this is true?
-kane
\_ it sounds apocrophal
\_ It is a true story. The student was George Dantzig - android.
\_ And what was the problem?
\-I dont know the problem, but the answer was the Simplex
Method. --psb
\_ actually, i heard a similar story about John Milnor which goes like
this: Milnor was in an undergraduate class at Princeton and came in
late-- the prof had put an unsolved problem on the board and Milnor
thought it was homework-- the problem was: is there a minimum turning
angle for a nontrivial knot-- Milnor went home and proved that a
non-trivial knot most turn though at least 4*pi (two revolutions)
and so he published his first result at 18 years old-- kinda makes the
rest of us mortals sick-- jkin
\_ And I heard a similar story about someone different. I think the
blackboard /homework part is apocrophal (or at best, exaggerated)
even tho the underlying problems and people are real.
\_ http://www.urbanlegends.com

11/13 People wishing to be involved in a sort of combative automata-type
contest not dissimilar to Core War which will be taking place in
Texas on November 30 should contact me PDQ. It looks to be a really
classy gathering with guest speakers and stuff. Team of 3 undergrads.
-blojo

12/7 There is some sort of showing of a work in progress of a movie
of the book 'Neuromancer' at Mills at 9pm on Friday.
Anyone interested in going with me? -danh
\_ Currently, we're thinking of pub trans... anyone drive? -marco
\_ sparky's
\_ anyone willing to risk the Payam-mobile can go with me
\_ 1 space left
\_ It is showing at 9pm at Mills College Concert Hall,
5000 MacArthur Blvd., Oakland, CA. Supposedly AC Transit
bus lines 57 and 58 N stop directly in front.
mail snol@mills.edu for even more detailed info. -danh
\_ Mebbe we should meet someplace in Berkeley so the AC Transit
clueless (like myself) don't get hopelessly lost in Oakland.
-sameer
\_ I can pick up and take 1-2, or 3 really uncomfortably but,
it's free and not that long a ride. -thorn
\_ I'd be willing to drive a load out, too. --ERic
\_ Anyone have enough room to give me and my email babe a ride? - danh
\_ How fat is she?
\-this a virtual babe?
\_ I might be able to make it. If so, I can drive people. -phr
\_ if i can't find a spot in a car, i might offer a spot on the back
of my Suzuki. -hh